Meech17
WotC President Runner-Up.
I've been thinking about this lately. There's way too much overlap here. I mentioned in a post further up about perhaps just having four main classes and then tons of subclasses,Another change I would make in a proper 6E is eliminate the arcane overlap. You don't need wizard, sorcerer and warlock. In a perfect world, you could have a single arcane class and use something like subclasses to illustrate their path to power. In fact, I would probably just do that across the board with fighters, clerics and rogues too. It would help with the broadly applicable subclass idea, too.
but at the very least I would combine the sorcerer and warlock. Leave the Wizard as is.. Being the "Developed Magic through knowledge" class.. Have the different schools of magic, the ability to scribe new spells, etc.
Then have the SorLock be the natural magic class. Warlock could be a subclass just like the Dragon Heritage one. You've developed magical abilities and powers through various, non-trained means. Perhaps that's the dragon blood running through your veins, or the deal you made with a dragon a hundred years ago.
I would also totally separate their spell lists. Maybe allow them share a couple of simple spells, but for most part they'd be entirely unique.