"Maybe the oligarchs will replace Putin with someone more inclined to grovel to US interests ? " ...... back in 100 years ago the yanks started interfering with other countries to build business empires. damn right they did. and then the CIA formed and started US State activities. I'm damn certain you know all this.
I consider a number of angles on Biden's reactions to Russian troops almost surrounding Ukraine.
Of course Putin wants to extend his empire too. Ukraine has often been a bone of contention, as well as the birth place of much that made USSR able to survive the appalling maladministration of communism and the insane tyranny of Stalin, Brezhnev and Kruschev. Putin, imo, doesn't recognise the effort of Gorbachev to free Russia from the tyranny and I gather Putin sees this as a national disaster. Putin longs for life adoration from his people. he wants to lead them until he dies and be buried in State alongside his idols, Stalin, Brezhnev and Kruschev,
but I cannot understand your rationale for your view of US intentions. Sure Biden needs a poll booster so of course he might look around for a conflict..... but to pick a biff with Russia? no POTUS would be that dumb

..... even Trump made pals with Putin.....