I think this is it. Have a Warrior class and have Ranger, Fighter, Paladin, Monk, etc, be "kits" that extend from it.
Have a Priest class with Cleric, Druid, and Favored Soul kits. A Mage class with Wizard, Illusionist, Warlock kits. Rogue with bard, thief, and ninja kits, etc. I think...