Yes he has his back to a wall; but Putin is seasoned, hard core and wily as a strategist and a politician.
With trillions of dollars sanctions against him he will now feel justified to take military action.
The EU (Europeon Union) is at present not in a position to take on Russia's military might, and not that they would be eager to get into this broil, with or without the US overtures towards them.
So what do we have now?
Vladimir Putin has a free hand with Ukraine with his military might: and the rest of the world can do nothing about it, since they have already done their worst via sanctions (albeit justifiably so to many!); and Putin will feel justified in taking over an industrial Ukraine to make up for some of his loss!
Given that the world does not want a third world war against a determined man who has nothing further to lose (and one must not forget Russia's 'affinity if necessary' towards North Korea), an imminent Cold War is just what Putin would want, to his own benefit!
I had said before that Vladimir Putin does not take things lying down.
As for the US, they too would not want a war with Russia. My respects to that great nation.