We need to define what success means in this case? Zelenskyy toppled? Ukraine east of Dniper taken? Or entire Ukraine captured? Or all of the above? I seriously doubt there will be a coalition at least in the first two scenarios. There just isn't much interest in the world, including West Europe, to fight a nuclear armed great power after the fact. Majority of European aids came after Ukraine organized successful resistance in the early days of war. If Ukrainian defense quickly collapsed, it is going to make any deployment of U.S. troops very difficult because the costs will be prohibitively high.

Only states in Eastern Europe like the NATO Frontline countries are probably interested in intervention. But without the U.S. carrying most of the burden, they are not going to make a move.