They have stated that EA will only have a subset of everything that is v1.0.
This means that there will be new experiences (this can include new subclasses) that was not part of EA that will just show up in v1.0.
Yes they could do that, but I do not even think there is 1% chance all PHB subclasses will be in BG3 v1.0.
They explicitly said all of them would. considering how rare it is for Larian to say things explicitly, I assume it's true, or at least the plan
And I think - on top of that - the many modders plan to add stuff that is part of Beyond, so people will see subclass options outside of the PHB. Possibly, races, spells and other things.
Larian also has the option to include additional Class/Race options as part of any new module DLC they release. I mean the game seems certainly set up to accommodate that anyway.
So chin up OP.
