\1. I don’t see a scenario that would have Putin’s win in Ukraine, even if he conquers the whole country, have him in a more geopolitically advantageous position that he was before 2014. Before 2014 Ukraine was a staunch Russian ally, almost like Belarus. The current situation is like if a Russia-aligned PM got elected in Canada, the US declared war, and would still be fighting having lost most of its army over almost a decade.
But aside from that let me go doomer even harder.
2-4. That would almost certainly result in a civil war or a coup in a very short amount of time. As soon as NATO is not keeping the world order, global commerce, thus the value of the dollar as a reserve currency for global trade up, the US economy will enter a never-before-seen recession, possible hyperinflation, which Trump will need to deflect from. My money is war on Mexico or Cuba. Or both.
5-8. There is a big chance that France would make good on their policy of first strike with their nuclear weapons before Russian soldiers would get too comfortable on European soil. China and the US join in since the Russians start shooting everyone out of force of habit. The Earth is now uninhabitable.