The BIG problem is todays everything goes mentality as in everything HAS TO GO.
That's why I voted there are to many already.
Create as many subclasses as you like but within context. Ok for official FR products it does not matter much because FR is the new Eberron already
But for other campaigns I just do not want the would be player of an oath of furuncle on the bum paladin complaining, why I would not allow his special subclass in or could not fit it in.
People today think it cannot be diverse enough, but they do not see the forest because of to many trees.
To much choice is not helpful in any way, especially because even with the standard PHB you got myriad of options to customize characters using backgrounds feats and mc if it need be to portray anything you like.
Why does a bola swinging fighter need a bola swinger subclass?
Why do we need a parcours expert class for roof jumping rogue?
With only so many spells available why do we need additional mage subclasses?
I get it for some it seems to be fun and some feel their character concept is so special that it should get a dedicated class, but I see no advantages in that.
Rather create subclasses fitting for a campaign e.g. FR purple dragon knight that is ok for me. Unless said purple dragon knight turns up in my dragonlance/eberron/greyhawk campaign.