GT5: The PS3 doesn't have a large install base as the PS2 had when GT4 was released so I expect GT5 to sell less, 7 million I guess (which is very impressive for a PS3 title).
DKCR: Has the potential to save the WIii and Nintendo (once again) just as the first did for the SNES, with more than 75 million Wiis at the release time it can sell more than 10 million but I don't believe it will reach 15 million.
Zelda: Historical data shows that Zelda is not popular as GT and DK, Twilight Princess managed to sell very well (Wii GC combined) and been one of few motion plus exclusive titles can help on its sales. In addition, a bundle or a different box cover can help as well. What about the saler? 6 million I guess.
That is is it, in my opinion: DKCR > GT5 > SS
