I'm going in a bit of a different direction here. Given the 4 PC groupings, I'm guessing that the 4 subclasses for each class will end up representing the 4 Class groupings for each class. You'll have the 'classic' class for each that is the 'pure' version of the class, with the others dipping into the other three groupings. Don't know if that will stick, but I think they may want to test it. While I've used traditional class names for the below, I think there will be significant changes (including name changes) to fit the below.
Barbarian: Berserker (Warrior), Totem (Expert), Ancestral Guardian (Priest), Storm Herald (Mage)
Cleric: Life (Priest), Forge (Expert), War (Warrior), Arcana (Mage)
Druid: Land (Priest), Moon (Warrior), Dreams (Expert), Wildfire (Mage)
Fighter: Champion (Warrior), Battle Master (Expert), Eldritch Knight (Mage), Warlord (Priest)
Monk: Open Hand (Warrior), Shadow (Expert), 4 Elements (Mage), Long Death (Priest)
Paladin: Devotion (Priest), Conquest(Warrior), Vengeance (Expert), Ancients (Mage)
Ranger: Hunter (Expert), Monster Slayer (Warrior), Beast Master (Priest), Horizon Walker (Mage)
Rogue: Thief (Expert), Swashbuckler (Warrior), Arcane Trickster (Mage), Assassin (Priest)
Sorcerer: Storm (Mage), Shadow (Expert), Divine (Priest), Dragon (Warrior)
Warlock: Tome (Mage), Blade (Warrior), Chain (Priest), Genie (Expert)
Wizard: School (Mage), Bladesinging (Warrior), War (Priest), Scribes (expert