Back in 2012 we thought some of the other minorities might join the Alawites as relatively enthusiastic supporters, since their position in a post-Assad Syria would be pretty precarious. But this hasn’t really happened — support sometimes, enthusiastic no.
The majority of Assad’s combat troops are Alawites, because he can’t trust anyone else. That’s why he has to supplement with Hezbollah and the Iranian Revolutionary Guard and whatnot. Even so, this means he’s perpetually, desperately short of manpower.
Sure, I could imagine a scenario where the government gradually rolls up the cities and large towns, one by one, and slowly strangles the various rebel groups or drives them out of the country. But it would require levels of administrative efficiency and resource mobilization that we haven’t really seen yet, and some diplomatic chops as well. (Or full-scale Russian intervention, which is not going to happen.)
My prognosis: no Assad victory this year. 2017 could theoretically happen but I would bet against it, even with a very generous definition of “victory.”
Caveat: replacement of Assad by someone more palatable or competent could throw things up for grabs. Assad is of course aware of this, which is why his personal security is very very tight.