BioWare + Star Wars failed, which is, er was, a very serious challenge.
I think the only property that could provide a real edge on WoW is Discworld (Harry Potter could have at one point but not now). The various other obvious candidates are already licensed and/or are associated with existing or failed MMOs.
So who would make "Discworld the MMORPG"?
Bethesda + Discworld?
Rockstar + Discworld?