No Selnor, GT sales are not on the decline.
GT 3 > GT > GT2 > GT4 (Which was up-adjusted from 8 mil to 9.5 mil, woot).
So they are not on the decline. Unless you count in random order. Fail.
OT:
Probably announcing the XBOX 720. It's not like games are really game-changers in the console fight. It has to be a new console. Slimline or 720, one will be announced at E3 2009.
On a side note, yes MS has done good at making sure that at E3 they only talk about things on the horizon, but at TGS they announced Halo 3: ODST a year before launch. So there goes that theory.