Yes. If they trade. If not, Columbus could singlehandedly end all future transfers of USMNT players to MLS by simply holding onto their #1 spot.
Or is there a use it or lose it policy?
use it or lose it. I forget the exact details from when it was announced, but if they lose it, the team that uses it does have the pay the team that doesn't a set amount (MLS extortion $) for the privilege.