A disclaimer. I really don't think this will fly. Not that it's impossible to write such a system for an FRPG, RuneQuest did it, Warhammer kind of did it, GURPS Fantasy (and others) certainly did it. So you can certainly write coherent and successful FRPG systems that don't have character classes and don't have levels. However, would they be D&D? If you think of D&D, what do you think of? If you're of a certain age, you might think of the satanic panic. Or the cartoon show. But typically you think of a party with a fighter type, a thief type (now reframed as a rogue), a divine caster type and an arcane caster type. If you're a bit less informed you go fighter, thief, cleric and wizard, a bit more informed you might say something like well it could be paladin, monk, druid and sorcerer instead, but you still think of those four roles. If you've played 5e, you might erase the cleric for a bard or a second combat character, and call them by their subcl...
This blog is written with the assumption that Wizards of the Coast lose their marbles and appoint me to be the lead designer for 6e D&D! It's not going to start as a serious play-test build, more outlining the ideas I'd like to see but if there is enough interest it might build up to more.