As far as I've heard, plans are on the way to split Syria and create a Sunni autonomous region (once the Islamic "state" is removed from the map), besides the Kurdish autonomous entity (if Turkey agrees) and an Allawite entity (under Russian influence) but without Bashar. With a bit of luck, that could work. The ISIS can't be defeated without winning the support of the Sunnis first (without whom there's no point in fighting ISIS on the ground). And the Sunni state in Syria can't exist without a solid international guarantee of the great powers that the Iranians (Shiites) won't retaliate. Which is made possible by the Iranian nuclear agreement.
As I see it, the US knows exactly what they're doing, and they've known from the start. The invasion of Iraq and subsequent retreat was a tactical move to set the region on fire as a way to counter the Muslim revolutionary ferment by turning the Muslim world against themselves, rather than the exterior. The migrants crisis (a Turkish tactical move) and the terror wave in Europe are of course a side effect, but I don't think the Americans are too upset about it, as a way to remind the Europeans of their own responsibilities, and to make clear that they can't expect the US to provide an unconditional protection umbrella forever while incurring all the costs (and while Western Europe is busy enjoying the benefits of their welfare states). Moreover, if Western Europe is going to play the Russian card (as they seem to have started), they'll be doing so at the cost of losing the support of the Eastern EU states and the EU & NATO disintegration, with the US remaining the only power to provide the security umbrella for Eastern Europe against the Russian unrest and ambitions (which, from a security standpoint, has anyway been the case since the fall of the iron curtain).
As for the Russians, their late few tactical victories are not going to prevent them from losing the strategic battle in the end. We've seen that movie before.