The amateurs that made up the numbers in London will be first to get binned. If they are sticking with the shotgun start then a 54 man field makes more sense than 48 tbh, so they do have a bit of wiggle room.
If they do keep attracting more players though then sooner or later they will have to cut players. Obvious candidates would be folk like Chase Koepka and the US Amateur Champ Piot, and the other guys who are 1000+ on the OWGR.