I can think of a way it might be done off one set of hardware depending on how VMs work with things like joysticks, but can't imagine bothering with it. I'd imagine it would be kludgy as hell, with inputs going to all vehicles currently being driven.
It could be marginally useful for operating in an area where there's no enemy presence, but just can't see it being useful in a crowd.
Wouldn't really work like WoW though, there's more to AH than targeting and clicking. Having to orient yourself in the game makes a huge difference.
Wiley.