Mario is going to win. Sunshine is the ONLY main series Mario game not to break the 10-million barrier (SMB2 reached it with combined sales of the 2 versions, and SMB, SMB3, SMW, SML, SML2, SM All-Stars, SM64 and NSMB all reached the mark as well.) And Galaxy seems much more like a "true" entry than Sunshine did. Let's put it this way: Sunshine selling slightly below Halo 1 levels was seen as so pathetic it was like a scandal for the Mario series.
One thing people need to consider with Mario is the co-op mode. Mario is certainly a "gamer's game," but its one of the most accessable gamer's games too. At Thanksgiving and Xmas this year, there's going to be a lot of kids or teens playing Mario, who hand Mom or Grandpa a second Wiimote to play sidekick. All they have to do is aim and click. Mario Galaxy's co-op is literally designed to be played together by one "gamer" and one "non-gamer." This is the X factor, as far as I'm concerned.
Even with a price cut, the price barrier for Halo 3 is going to be much larger than it was for Halo 2, and 360's momentum just isn't very good. The first two barriers Halo 3 needs to cross are Halo 1 sales and Halo 2 sales, before we even think about it selling 10 million. If it doesn't sell 10 million, it really has no chance of beating Mario Galaxy.
I do think Halo 3 will pass 9 million and take a run at 10 million in the long run. But I think Galaxy will do at least as well as SM64 (12 million), though not as well as NSMB (should do 14-15+ million).
I think Halo 3 vs. SSBB would be a better question. I really don't know what I'd pick there.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
