It’s a big ask for a national team to stay home. It’s more likely that a player or two might “be injured” and miss the games. However, there’s far more chance that the fans will stay away. It’s expensive getting there, and access control will be difficult for many team’s fans. The weather might also be bad for both the players and fans. Those with the ticket and travel info know but nothing seems to have been mentioned so far.

En masse, uefa could just move the games to Europe and invite Argentina and Brazil…

If you were a foreign national --- athlete or spectator, what are the chances you will be harassed or even detained? This is the worst possible time (so far) to visit the U.S.

Just give Trump a shipping container of medals and carry on the sport elsewhere. You have no Jesse Owens.