I don’t think the geography of that really works out.
Here’s the current situation (from http://syriancivilwarmap.com/). Unlike the Korean war, which was just drawing a line of control at one point along a peninsula, the current lines of control between the multiple sides don’t really allow this conflict to “freeze” cleanly. The Rebel held areas (green) are not contiguous- there are several areas entirely surrounded by Syrian Government held territory, and only few areas have a land border with external countries.
Also, take a look at this population density map:
This shows that the territory held by each side is vastly different in terms of population. Most of the ISIS held areas are thinly populated, which means that maps exaggerate their rise and fall. Also, note the light blue section, which is now controlled by the Turkish army, following their recent push across the border, which was in response to Kurdish pushes to join up the areas that they held. Who has that helped?
