Provided the US throws enough resources but it's the US that has to mostly flip it all from afar. And the likes of Russia or China are close by and don't have to lean out, they just have to throw the Americans out. The whole US Doctrine is expensive as hell, while Russia goes for a rather more rational Cost/Effect ratio. It is no longer the USSR which can afford deep operations, it is a country with demography destroyed by communism.
Frankly speaking, Ukrainians can afford losses and protracted war even more than Russia.
Because it's honestly no art to develop a plan for a quiet year or so, then bomb your target to hell because you do. After all, the Russians were playing with the West's noses all the time until they suddenly attacked Ukraine. Surprising almost everyone. And we still don't know what the hell they're talking about, because I don't really believe Putin's gibberish.