Heh. How about GeForce2 FX 6x00 or GeForce FX Ti6x00? A Ti6200 - Ti6400 - Ti6600 series akin to Ti4x00 would be :D, but it's not going to happen, with Ultra and whatnot, sadly. Perhaps Ti6800XT, Ti6800, and Ti6800 Ultra...
Oh, and for the record, GeForce PCX sounds horrible. Couldn't they...