So I had the idea while posting in the Orgrimmar thread. Sure, this will never happen after the flop that was Cata, but what if Blizz decided in 6.0 to revamp the Old World questlines again to reflect the death of Garrosh and the shift in power after SoO.
What would you want changed with the questlines? More focus on a race, less on another? Give a faction the ability to quest in a zone? Change the outcome of a zone's events?
One big thing I'd want is for Gilneas to become the un-instanced starting area for Worgen, and after Gilneas they can level through Silverpine, Hillsbrad, Arathi, Hinterlands, WPL, and EPL alongside the Forsaken.