I could see a Starcraft MMO, if they innovated on what an MMO could be.
For example, an interesting Character Progression could be centered around the same progression Jim Rayner experienced. He went from "lone Sherif on a backwater planet" to "Commanding General of an entire rebel fleet." But the SC2 campaign made clear that he still had plenty of reasons to get on the ground himself.
And no, I'm not thinking anything like Mission Tables...like at all. It would have to be ambitious as fuck, some combination of EVE, Star Citizen, AI NPC's linked to your character, so they keep doing stuff in real time while you're off on another planet. Space and ground combat systems.... I'm dreaming of there being a truly persistent MMO world again. lol.
But yeah, don't expect anything to actually be made. lol.