There is a lot of good answers - by ignoring the real question.
New equipment for the Russian force must take the changed circumstances into consideration.
The cold war scenario of a massive breaking through an entrenched NATO defence of comparatively small depth is not in the cards.
The Russian must consider a defensive scenario with deep penetrations into Russian territory (how likely that is, is another question all toghether, as the likelyhood of anybody wanting to occupy Russia and deal with their problems is remote, but off topic as political). These penetrations could come from a number of direction by mechanised forces (as mechanised forces are the only that stand a chance of being supplied in the wide Russian space).
The defence against these will not be heavy armour, as these will run out of petrol and avoided by an invading force.
A boarder defence by light forces is not a likely solution, as it will most likely only yield massive numbers of prisoners.
Thus not only is much of the Russian equipment outdated; but constructed to a wrong campain.
It seems to worst for the air force, as the inventory of short range interceptors and attack planes isn't very suited for the sort of warfare at hand:
A defence in depth depends on at least contesting air dominance in areas of the enemy's choice - otherwise they will end up like the Iraqi division stopped by B-52's. Perhaps that is the reason for the hopes on the Flankers.