Gutless, short-sighted, sh**t-headed, etc. politicians should find a solution because finding a military solution becomes too dangerous. Lock them in a room and not allow to get out until they come to a (compromised) agreement.
E.g., IMHO all sides should admit that division of the Syrian territory is inevitable nowadays. It already happened de-facto.
"Former dentist" (Assad the son) is unable to regain the whole territory after the coalition started military support to rebels (no matter who they are and how they are organized). Conversely, all those rebel groups cannot defeat the governmental forces, especially as they are supported by Iran and Russia.
So, the separation line(s) should be drawn and agreed upon.
Then, the entity controlling each zone should keep fighting ISIS, Al-Qaeda and likes, but not in the fashion like it sometimes happened in Mosul and Raqqa when special corridors were arranged for jihaddists streaming them to fight governmental forces.
Maybe in the future, the country could re-unify within the former borders, but some skepticism obviously exists because we all know/read how these borders were established after WWI.