I would be shocked if they didn't bring in two overage players here. Campbell, Dietz, and Neal are innocent. All three have good futures. None of this trio is ready to play significant minutes for a team expected to medal in Paris.
Assuming Tim Ream, Chris Richards, Miles Robinson, and Cameron Carter-Vickers are the top four players on the USMNT depth chart, those four will be called up to this summer's Copa America, and four will not be asked by anyone. He can't even participate in the Olympics.
The next two players on the current US cornerback chart are Walker Zimmerman (if he can get healthy) and Mark McKenzie. I think it's possible that one or both of them will be released, but 1) MLS teams tend to play well with US programs for the most part, so if Zimmerman is called up, they'll let him go; It would be a shock if he got called up, and 2) Genk is a selling club and the Olympics are a hell of a shop window, so I'm sure they'll play well with McKenzie if he gets called up.
I also really like the possibilities of this combination. Zimmerman is dominant in the air and covers up for McKenzie's relative weakness, but while McKenzie is a very good distributor, Zimmerman is not.
Auston Trusty (Sheffield United) could do well here given his history with Philadelphia Union center McKenzie, but I don't expect him to feature. If the U.S. is forced to add more depth to their overage roster…maybe Seattle's Jackson Ragen?
Anyway, my predictions here are two overage players and Dietz, but if Campbell starts to slip (he's been good so far in Montreal, but not great), or That could change if Neal returns from injury and earns a starting spot for the Galaxy.