R600 will even go external and will make some crazy multi monitor setups and will allow more than just four or six displays setups. We know that AMD is working on such a card and it will probably launch it together with super delayed "everyone gave out hope" R600.
AMD thinks it can solve the bus limitation and from what we know it should give Asus XG station runs for its money. We know that the prototypes are up and running and we don't know how many people will actually want one.
There is a market for that card as there is a whole world full of notebooks with Intel integrated.