I think Uncharted 2 will be a system seller, we will have to wait and see. But like someone said it all depends on how you define a system seller, but i would say it's safe to say if sales are down on averages a week or two before, and then above average after the game is released you could call the game a system seller.
As for calling Gran turismo like a Halo, i think you need to look at the numbers. Only Halo 3 has sold anything similar to a full gran turismo title, i think Halo is still a way off reaching the heights of gran turismo. Especially when the Halo story is really starting to wear thin, and Bungie has made it very clear Halo Reach will be the final Halo game made by them. GT is a franchise that will continue to live on for as long as there is cars and video games.







