I know this already happened on a smaller scale in Twilight of the Aspects, but if there was a WoW 2 (There won't) I've always thought it would be cool to base it around the Infinite Dragonflight, who have caused Thrall to die before being discovered by Adelas Blackmoore. His death would effect more than just Lordaeron after all. There would be no Horde as we know it, no Night Elves in the Alliance, Tauren would be scattered and possibly extinct etc.

I think it'd be pretty interesting to see.