After the presidential election whoever is in will have to find very large sums of money somewhere out of the current budget - I can't see the navy wanting to lose their new "Ford" carriers or the new SSN's - the Army couldn't give a toss about the F-35 sooooooooooo the USAF will be on their own
not a comfortable place to be
I also suspect once one "partner" pulls out the rush to the door will be amazing - thsi has happened on a number of "collaborative" projects worldwide. No-one really wants to be first but needs must when the devil drives