Realistically no one is going to invade Russia.
It still has either the greatest or second greatest nuclear stockpile in the world. So what if NATO expands into Ukraine?
I think that Putin kept the conflict minimal (minor border skirmishes) like many analysts have predicted then he could’ve achieved far better geopolitical outcome. Going all in like this is very detrimental to Russian interests.
Going forward Europe may no longer exist as an independent pole, and neither would Russia. Only long term beneficiaries are on the opposite sides of the Pacific.
In Putin's first speech he explained it. Ukraine is culturally important to Russia. Seeing it turn into another western client state is a slap on the face. Ukraine's military importance is being overhyped by both sides, especially given that the Baltic states are already NATO members.
It's very difficult for both Russia and America. If lots of Ukrainian and Russians start dying the war will quickly become unpopular. Meanwhile the west needs to balance their condemnation and punishment of Russia with their own public sentiment both pro and anti war. Biden is an old man and he's said very little about this conflict. His opponents will jump on any sign of weakness.
The worst is yet to come in the west. In the UK people are already getting gas bills that are 4x higher than what they normally would be, and that was before this conflict started.
I'm sure if America could go back in time, they'd agree to Russian demands about Ukraine. It's not like NATO is that relevant today anyway with China being the emerging power.