Enter the Frankenstein server hypothesis.
I really hope I am wrong about that, but unless something has changed in the equation of blizzard, activision-blizzard, maximizing revenue, and a/b infamous 'accessibility' ideology, that is likely to be what we get. Any single-difficulty aspects which have some challenge may represent blizzard's best effort holdout against total nerfing of leveling (outdoor and instance) content.
the fact they clearly circulated a memo to use the phrase 'the classic gaming experience' or some derivative thereof, emphasizing the word 'experience,' is a major red flag. They can claim to have provided the experience while gutting the game.