I think Blizzard should take the harder, but more rewarding road of disintegrating Outland and Northrend from the leveling cycle and reducing the XP curve from 60-80 so you can level in that bracket faster without having to leave EK or Kalimdor zones. For example, instead of Silithus being 55-60 it will be 60-70 and previous zones are stretched upwards as well. Hyjal and Vash'jr can be stretched down to 70-75 and 75-81, and at 81 go into Deepholme or Uldum to continue as normal.