Oofta
Legend
The problem with that is the people who like and want to play, say, eldritch knights now no longer have a resource. You may not prefer the subclasses from the PHB, but not including them doesn't seem like the right way to go either.If they reprint the PHB for the anniversary, I feel like it would be smart of them to not reprint all the same subclasses and instead try to cover similar conceptual grounds and adding new ones and even reprinting stuff from Xanathar and Tasha's. That way, regardless of which PHB version you own, you can still play a simple incarnation of every class and the core Class remains the same, but you also get different choices to pick from, and there would still be value for someone to pick up both version. This would entice previous player to pick up the new version.
I could see all the SRD subclass kept in. For exemple,in the Fighter they keep the Champion, replace the Eldritch Knight by the Rune Knight, and add the Tasha maneuvers and fighting styles. Then for the Rogue they keep the Thief, but replace the Assassin with the Mastermind and add a new magical subclass... that sort of thing.
I don't know if there is a great solution. You could easily have a book of just a consolidated subclasses, feats and spells with nothing else but then people would complain about that as well. Also something you can get with a subscription to DndBeyond.