Honestly the smartest thing Blizzard could do right now IF Classic succeeds well and truly, is to make "retail" a mobile game and add on new content to Classic and keep it on PC.
What's the point in having worlds or quests etc when people just want to end game LFR spam/pvp spam? what the point of having the world when there's no community lol?
It would actually make the perfect mobile game for people who "don't have time" they just want to get in collect loot/skins and get out with in a few hours.
If people want to raid and clear "hardcore mmorpg conent" go play Classic.
Win/win for both player bases.
And Bli$$ard get's the $$$.