Indeed, Classic players who like it so much they want to keep playing will keep playing Classic, but won't touch Retail even if it becomes "closer to Classic". Those that don't prefer Classic want a Retail that's not that.
Activision Blizzard, sure. But not Blizzard themselves. And definitely not WoW. Overwatch, Hearthstone and HotS live off lootboxes, card packs etc., sure, but the subs themselves will always top any mount&pet purchases overall.