Putin needs Syria.....he doesn’t need Assad.
Correct. Putin also needs the US if he can have the right kind of relationship. Russia is not wealthy and still struggles under the corrupt oligarchy. Putin has built his power base on controlling that and creating as much wealth as he can, and he will factor these choices through that filter.
Putin, Assad, and Trump all want to see the end of ISIS. Two of those three will still be in power after ISIS is gone. Guess which one might not?
He wants a port there as someone here explained.. He needs assad. Deal with the devil you know...not one you dont