Sacrosanct
Legend
You kind of missed the point.
You said you needed "...more feats and subclasses to flesh out the most common archetypes." I assumed that was your point since that's what you actually said. And if we're talking about the most common archetypes, then 5e does that already. From your other statements, it seems that what you actually meant was that you wanted more feats and subclasses to fill your niche and/or highly specialized concepts. You can hardly blame me (or others) for missing the point when your point was something different than what you actually wrote.
Addressing your actual point, my suggestion would be to not hold your breath. 5e is not going to be like 3e with a ton of specialized feats and classes. It's not designed to be so. I for one would not want to see the feat/class bloat that plagued 3.x in 5e. And I have a suspicion that WoTC isn't going to take a business model where they put out all that material either. Splatbooks and fluff for small pockets of gamers isn't something I see them putting out any more. What I do see?
An Adventure Path that includes another variant of sorcerer, possibly a psionist, and additional specialties for clerics. And that's about it.