Europe already learned, the hard way, what happens when you try to placate an authoritarian with concessions instead of standing on principle. The memory of Chamberlain and the disaster of appeasement isn't some dusty history lesson there — it's baked into their politics and institutions. So the idea that Europe would let itself be economically strong-armed into treating territory or self-determination as a bargaining chip underestimates both their history and their resolve. They may absorb pain, they may retaliate, they may negotiate — but they're unlikely to get suckered into repeating a mistake that once cost the continent everything.
But I guess we'll see!