Hard to comment given the recent political changes happening, might get a more concrete view after Trump comes in.
So far, following the recent activity, Assad's control over Syria might enable them to get control back ( and also adding how Trump administration sees these things as).
Good point by @DKC
"Attempts to rehabilitate Assad are picking up steam. Several European countries — including Italy, Hungary and Greece — are keen to abandon the current policy of isolation. They want to return Syrian refugees to the country despite the unwillingness of the regime to pursue genuine reconciliation. They hope that in exchange for financial support and political cover, Assad will agree to allow back large numbers of refugees living not just in Europe but also in Jordan, Lebanon and Turkey. "
Passage of time and less time overall