Assuming there is no finality to the conflict by March, the Syrian war will by then have been raging for two years, one which, if it has not already, will soon have claimed over 60,000 lives (how the UN came up with this figure is actually fascinating itself). Considering that this story has been on and off U.S.' front pages for a couple of years, it would be hard to see an end coming, yet rebels continue to strike important military bases and make incremental, bloody gains. President Assad has retreated from any semblance of public life, reportedly living in a pretty paranoid fashion.
With the New Year, the question being asked more often is not "if" the Assad regime will fall, but "when" and "how." Will Assad finally succumb and go into exile before it all collapses around him, or will he die in a fashion similar to that of the late Libyan leader, Muammar Gaddafi?
Two more concerning questions than Assad's ultimate fate, however, make Syria a giant security concern for 2013: whether or not Assad will use chemical weapons, and what sort of government will replace him.
Reports in early December had the regime preparing sarin gas, an extremely deadly nerve agent, to be dropped from fighter-bombers, although later reports suggest that such preparations were slowed, if not stopped. The worry is, however, that, once Assad becomes desperate enough, he may risk their use in order to try and save whatever remains of his regime. The result could be the deaths of thousands, if not tens of thousands, with the casualties almost certain to be comprised mostly of civilians.
President Obama has previously called the use of chemical weapons a "red line," and Assad's use of them would very likely draw an international reaction involving military force. Assad knows this, and in my opinion, this has been the primary reason why they have not been used already. The longer the conflict continues, however, the more time it gives Assad to change his mind and go ahead with the strikes anyways, which would almost certainly become one of the world's low points of 2013.
A separate-yet-related concern has been what will follow the Assad regime. The U.S. and many other countries have given formal recognition to the Syrian Opposition Council. The group has had some success at beginning to organize the very disparate groups that comprise the opposition, but its hold on legitimacy once the conflict ends is tenuous. The fact that the current regime is run mostly by the minority Alawites has many fearing reprisals, and the numerous different groups in Syria – including Alawites, Sunnis, and Kurds – has some fearing sectarian conflicts could occur as result of a power vacuum.
Just as big a worry for the West has been the role of extremist groups within the opposition, with the U.S. last month designating one group, Jabhat al-Nusra, as a terrorist organization. The group has seen several battlefield successes, but it's unclear what the true level of support for them in Syria is, as many have been drawn to the group by a lack of funding and weaponry elsewhere (lending credence to the argument that lack of outside support has helped increase extremist presence). Nevertheless, the last thing the U.S. or other countries want is such a group wielding significant power in a new Syria or, worse, getting its hands on Assad’s stockpile of chemical weapons.
Overall, I think few would argue at this juncture that Syria would be better off with Assad remaining in power, and the fall of his regime would at least provide hope of a future democratic Syrian government that does not shoot at the first sign of discontent. But that is still well into the future, with many lives certain to be lost in the meantime. The continuing bloodshed, as well as the concerns laid out above, make Syria perhaps the defining international security topic and concern of 2013.