Huge missed opportunity with Ushoran for that last part. Not a fan of how they rewrote his lore.
In terms of characters returning, I'd just like to see magic focused vampires again. Mannfred used to be an incredible wizard, now he's 'just' a 2 caster with no buffs, same as all the other 2 caster wizards in the game, or worse. Necrarchs aren't represented whilst the other main bloodlines are. Vyrkos to some extent filled this niche with reroll casts, but they took that away.
My fear with AoS is they're focused too much on 'balance' and competetive play, all my armies (I have 4) have seen vast reductions in choice and variety to the point when I'm making armies I just have the same items and traits every single time. They've made unique characters incredibly hard locked (soulblight in particular) to the point you HAVE to use them in their subfaction. Traits and items have been cut in half or worse, magic choice is all disappearing.
Playing some Old World has really made me miss the customization and choice/variety even more tbh.