From the Russian perspective, they seem to view NATO encroachment into Ukraine as an existential threat to their survival. IMO they will not cease hostilities until their objective of de-militarising and de-nazifying Ukraine are complete.
On the other hand, the West continues to escalate the situation and doesn't appear to care about Russian motives whatsoever.
I don't see this ending any time soon; neither side appears to care for the motives of the other and so far show no signs of backing down.
Will the West ultimately accept a Ukrainian defeat if that's what it comes to, or if that's what it takes to avert nuclear holocaust?
What do you think?
I think you may have that a little backwards. Currently Russia is doing just fine, using a fraction of their full military potential as Ukraine burns through their own armies and supplies (which already happened for the most part a while ago) and then NATO stockpiles. Russia could keep this up for a very long time and be just fine. The big question is whether NATO (in other words, US interests) will seriously escalate the situation and bring us into WW3.