Well, Crawford has stated that all of the above are the case, so it's a mix. Each Class is getting 4 Subclasses, which means more for everyone but Wizard and Cleric (though Crawford has pointed out the old Subclasses still work with the new chassis, so nothing is "lost"). What we know for sure:
- Barbarian
- Berserker ('14 PHB & SRD)
- Bard
- Dance (new, mentioned at summit)
- Lore ('14 PHB)
- Cleric
- Life ('14 PHB & SRD)
- Druid
- Circle of the Moon (NOT in the SRD, '14 PHB)
- Fighter
- Champion ('14 PHB & SRD)
- Monk
- ?
- Paladin
- Devotion ('14 PHB & SRD)
- Ranger
- Hunter ('14 PHB & SRD)
- Rogue
- Thief ('14 PHB & SRD)
- Sorcerer
- Dragon ('14 PHB & SRD)
- Warlock
- Fiend ('14 PHB & SRD)
- Wizard
- Evoker ('14 PHB & SRD)
- Necromancer ('14 PHB)
So, we know 13 out of 48 Subclasses for aure, based on things the designers have said or playtest packets. It's a pretty safe bet that the PHB Aubclasses not Cleric or Wizard are super likely, though I suspect that Four Elements might be replaced with Sun Soul from SCAG/Xanathar's. There is a lot of room for expansion or new Subclasses, as the designers have said theybare doing.
The flavor text for the Warlock test namdrops Fiends, Fey, Eldritch abominations, Celestials, Hags, and Undead. I think Celestial Patron is a pretty good bet to round out the PHB 3 for the Warlock, to balance out the options.
We know already we are getting the Evoker and Illusionist, so Schools are still a thing for Wizard Subclasses. I think Illusionist is likely, for historical reasons and it offers something different, and Bladesinger is super popular so that could round it out.