> Everything could change in a presidential election

A lot can change, but not everything. Trump won twice and republican elites are fully behind him. Even if he looses, the same ideologies will continue. It happened twice, it is not a fluke but a permanent property of American politics.

Moreover, constitutional changes supreme court created are structural change. They will be super hard to undone - first they would need to change supreme court composition. The influence of money in American politics will just grow, the structural advantages of conservatives have in voting system will just grow and next conservative president will have even more space for maneuvering. (Non conservative one will likely be stopped by supreme court on some excuse.)

So, basically, outside of change actual constitution which is impossible, it will stay the same at best in the long term.

I agree with everything you have written here, however even in the face of that it makes “economic” sense for the EU to wait it out.