Russia is allied with Assad and ISIS is toast in a month.
ISIS isn’t going anywhere. I’d bet my house on that. No ISIS, no reason for Russia to test NATO alliance & air space in Turkey. Comprende?
Dead in a month.
In fact, Assad has what amounts to almost (almost) a tacit cease fire with ISIS & has largely ceded a large area around Raqqa, and along much of the Euphrates River to ISIS.
This may simply be conservation of resources, plus to some degree letting the Kurds and ISIS, and others, duke it out in the North, while Assad tries to hold off the non-ISIS rebels near Damascus.
It's going to be very difficult for Russia to destroy the majority of the various anti-Assad forces from the air. Russia can certainly hurt them, but, eventually, boots on the ground will be needed, and in a big way. Ground support from Iran would basically involve Shiites vs. the 80% or so Sunnis in Syria (supported by Saudi Arabia, and in some cases, by the US). As ugly as the situation is now, it has the likelihood of getting much worse...
One of the really interesting questions is: What does Putin need SAM sites in Syria for?