Distance matters less in the modern world. I don't think that is much of an issue.

UEFA has nothing to gain from joining with anyone. They are already by far the biggest TV market in the world. They probably need to shrink - winning the Euros is harder than winning the World Cup.

Copa Libertadores, that's different. They could create something bigger and more valuable by adding MLS and Liga MX on a more permanent basis. They might want to consider Japan while they are at it.