Damnit, I wrote a relatively long reply, but VGC decided to delete it -.-
Anyway, short story.
Wii Fit vs Ps3 gap is smaller than Ps3 vs X360.
Wii Fit vs Ps3 gap: 6.2M
Sales last 2 months:
Wii Fit: 3.2M
Ps3: 1.9M
After the holidays, I expect the gap to be 5-5.5M.
So Wii Fit would have to outsell Ps3 by 100K weekly to make it (as the difference in the holidays won't be a lot larger than 100K, holidays doesn't flaw that up, but say 80K).
As we can say Ps3 will sell somewhere around 11-13M next year (probably), this means Wii Fit would have to sell 16-18M.
If we assume 3M for December, this means it will need ~ 250K weekly at least to beat Ps3.
That is possible, but very optimistic. I'll say no.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS