(CNN) -- As the crisis in Syria intensifies and Bashar al-Assad's hold on power starts to unravel, concerns are mounting over what may come next for the beleaguered nation.
Some foresee bloody sectarian strife or a descent into militia rule, while others fear what might become of its chemical weapons stockpile.
Not all observers agree it's the beginning of the endgame for al-Assad, but all are sure there's no clear road map for what lies ahead.
The prospects for al-Assad are "very grim," said Shashank Joshi, an associate fellow at the UK-based Royal United Services Institute think tank and a doctoral student at Harvard University.
"There's no going back," he said. "He's not far from collapse, because what's occurred through defection or assassination is that the political part of his regime has been hollowed out."
By contrast Dr. Dan Plesch, director of the Centre for International Studies and Diplomacy at the School of Oriental and African Studies in London, considers it too soon to write al-Assad out of the picture.
But in a scenario where he is pushed out -- bringing to an end four decades of rule by him and his father before him -- the Syrian military will likely play a major role in what happens next, Plesch said.
Recent defections of high-level officers -- notably regime insider Brig. Gen. Manaf Tlas -- on top of the desertion of many rank and file personnel, signal an erosion of the army's coherence in the face of the rebellion.
Many of those at the top are determined to fight on to the end because they fear the personal consequences for them if they lose, analysts say.
In what some saw as a turning point after more than 16 months of violence, al-Assad lost four top aides following an explosion in Damascus last week, as rebel forces attacked the capital and Syria's commercial hub, Aleppo.
So far, al-Assad has shown no signs of quitting. But what's not yet clear is how much stomach he has for a continued bloody conflict, and whether he might be more inclined to negotiate a transition than some of his immediate entourage, Plesch said.
If al-Assad's ouster were the result of a "palace coup," involving negotiation between some insiders and the insurgency, slightly more continuity would ensue, said Joshi. However, such a transition is likely to be unstable because many rebels would refuse to accept it and would fight on.
He believes it more likely that the regime collapses entirely and the Syrian National Council -- an opposition coalition whose leadership resides outside of Syria -- stakes a claim to lead the transition as part of a coalition also involving opposition figures within Syria and Kurdish and liberal representatives.
However, unlike Libya, where the National Transitional Council presented a fairly unified voice as Gadhafi's regime crumbled, the opposition in Syria remains more fragmented and no credible transitional leader has yet come to the fore, Joshi said.
Plesch agrees that while the Syrian National Council "aspires to be the linchpin in the transition," questions remain over how effective it could be and what support it commands among rebels on the ground.
Ausama Monajed, who advised a previous president of the Syrian National Council, told CNN in March that his group has a plan for a post-Assad era, including the formation of a transitional unity government and a body to draw up a new constitution and election laws, leading eventually to parliamentary and presidential elections.
At the time, observers responded with skepticism. "There's a lack of coordination amongst the insiders, and they represent the outsiders, not the insiders," said former U.S. ambassador to Syria Edward Djerejian. "It's not a coherent opposition leadership."
Another scenario sees Syria descend into a chaotic and bloody sectarian conflict, pitting Syria's majority Sunni Muslims against the ruling Alawite sect, an offshoot of Shiite Islam, and embroiling its Christian, Druze and other minority groups too. Such a conflict risks destabilizing the wider region.
The recent defection of two key Sunni figures, Tlas and Syria's ambassador to Iraq, Nawaf Fares, means all al-Assad has left is a narrow Alawite bloc with shrinking public support, Joshi said.
If the regime collapses, the Alawites could retreat to strongholds in the northwest of the country around Latakia and attempt to reconstitute a state there, he said. Syria's Kurds could also seek greater autonomy, a move which would worry Turkey, which has a troubled relationship with its own Kurdish population.
However, Rime Allaf, an associate fellow at the Chatham House think tank, argues against making too much of Syria's sectarian tensions.
The regime "has been using the sectarian line, but the opposition and the rebels have increasingly repeated that they do not view it in those terms," she said. "So it's not the Alawites who are crumbling, it's a regime. ... It means many people within that regime, whatever religious denomination they are, they don't necessarily agree with the way things are happening."
Sectarianism aside, the large number of militia groups that have taken up arms across Syria will present a "significant challenge" to the country's future stability whoever ends up in power, Joshi said.
They range from the pro-government Shabiha militia groups, blamed by opposition activists for many of the more brutal attacks on civilians, to rebel hardline Islamist groups and local networks that have formed to protect their villages.
At the same time, the rebel Free Syrian Army, largely composed of soldiers who defected from the al-Assad regime, is more a loose organization of armed groups than a coherent military body, said Joshi.
He predicts that whatever Syrian government results from the conflict will not be in charge of its whole territory, a problem made worse by the porous nature of the country's borders. If the Syrian National Council ultimately does take charge, it may struggle to contain the worst excesses of the militia groups, he said.
The International Committee of the Red Cross said this month that it considers the conflict a "non-international armed conflict" -- or a civil war -- but some analysts say international forces are in fact involved.
Opposition forces are being "quite well-armed and probably trained by external clandestine forces from the Gulf states and probably from Turkey," Plesch said. Questions should also be asked about some European and North American involvement, he added.
At the same time, Syria's neighbors, which include Turkey, Iraq and Lebanon, all have a stake in how the conflict plays out and exert varying degrees of influence within Syria.
Part of the international community's unease stems from Syria's position as a regional powerhouse. "Syria really is the epicenter of the Arab-Israeli conflict, and the international community's confrontation with Iran," said Plesch.
Another concern to those watching from the wings is Syria's stockpile of chemical weapons.
Syria's foreign ministry said Monday that the country has chemical weapons that it would be willing to use against foreign attackers, although it sought to roll back the message Tuesday.
Its remarks led to strong warnings from U.S. officials, including President Barack Obama, who said such a move would be a "tragic mistake."
Obama administration officials are now holding regular high-level meetings to discuss the ongoing situation in Syria and begin thinking about U.S. priorities in a post-Assad era, a senior U.S. official told CNN Monday. The Obama administration has also stepped up its discussions with Israel, Jordan and Turkey about Syria's chemical weapons arsenal
The al-Assad regime "probably has the largest and most advanced chemical warfare program in the Arab world," according to Michael Eisenstadt, senior fellow and director of the military and security studies program at the Washington Institute for Near East Policy.
But there is good reason to be skeptical that this arsenal would ever be used, Joshi said. Syrian commanders would not want to be held individually responsible with no regime to protect them, he said. Commanders are also well aware that the risk of such weapons getting into the hands of allies such as Hezbollah would likely induce external intervention, particularly from Israel.
For some observers, the international community's increasing focus on Syria's weapons stockpile also conjures unwelcome echoes of the run-up to the Iraq war.
Syrian allies China and Russia, who last week blocked another United Nations Security Council resolution for new sanctions if Syrian government forces don't stop attacks against civilians, are opposed to the kind of foreign intervention seen in Iraq as well as in Libya last year.
Moscow indicated Tuesday that Damascus should refrain from making use of chemical weapons in line with its ratification of Geneva protocols. "Russia's policy is based on the understanding that Syrian authorities will continue to strictly follow their international obligations," the foreign ministry said.
As for al-Assad, if he is forced from power, his personal fate will likely depend on whether he remains in Syria, and in whose hands.
A new regime might want to prosecute him for alleged war crimes or it might decide it would be more advantageous to allow him to go into exile, said Plesch.
Al-Assad's options for exile appear limited, with much of the world outraged by the thousands of civilian deaths resulting from his regime's crackdown on what it calls "armed terrorists." Plesch speculates that a country that is "not quite Russia," such as Moldova or South Ossetia, could offer a haven.
Alternatively, al-Assad could hang on to power for months yet, if regime forces and the Free Syrian Army continue to battle without a decisive victory on either side and the international community declines to step in.
So long as Russia and China continue to block tougher U.N. Security Council action on Syria, foreign intervention seems unlikely.
And although U.S. officicals have led calls for an end to the conflict, Plesch suggests that a prolonged conflict in Syria might not be the "worst option" from an Israeli or American militarist point of view, because neutralizing Syria would have the effect of isolating Hezbollah, and to a degree Hamas, from Iran, an ally of Damascus.
"If you are a Western security planner who thinks it's highly likely that there has to be a military confrontation with Iran sooner or later, then keeping Syria off the board is probably one of the things that's quite desirable to do," he said.
CNN's Holly Yan, Barbara Starr and Pam Benson contributed to this report.