Eureka! I think I know where the Su-35S will go. *drumroll* Krymsk. Airbase 6972.
After the latest round of shuffling, Airbase 6972 has become the class 1 airbase for the South MD. It has already taken deliveries of the Su-27SM3, which are good conversion and preparation for the Su-35S, and of the Su-30M2. Now it previously made no sense, since the Su-30M2 is supposed to be the trainer for all VVS upgraded Flankers, and each regiment in the Far East received only one Su-30M2, but the sole squadron of Su-27SM3s received a whole two of them. It would, however, make perfect sense, if they were meant as combat-trainers for future Su-35S. Even the numbers match up then, since 48 Su-35S are planned, they would need exactly two Su-30M2s for combat-trainer roles!
EDIT: This would also be consistent with MoD practice of sending all the newest and shiniest toys to the North-Caucus. Granted the Su-34s out of Voronezh seem to be an exception, but then again operating out of Voronezh, an Su-34 would be able to strike targets in the vicinity of Vladikavkaz, and return to Baltimore, without refueling (albeit at the limits of its combat radius). Given that the VVS has had quite a few in-flight refueling exercises with the Su-34, it's quite possible that they're counting on the tankers to extend their operating range. Finally, it should not be difficult to temporarily rebase some Su-34s further south if hostilities do break out.