Well, we have 19 at 1m now, so that gives us a good base.
I see nothing under 800,000 that I think will manage to get over the top by the end of this calendar year.
Of the games in the middle, Resident Evil UC, Pokemon, Sonic, and Lego Star Wars are likely to hit the top, and I'll give an outside chance to My Sims.
That puts the total at 24 before January 1, 2009.
Future releases?
Sure bets: Mario Kart Wii, Wii Fit, Animal Crossing Wii, Pro Evo Wii, Monster Hunter 3
Outside chance: House of the Dead 2 and 3, Mario Baseball, Sonic Tennis, Alone in the Dark, Fatal Frame 4, Disaster: DoC, Boom Blox, LEGO Indy, SW: Force Unleashed (would be a sure thing if it weren't MP), LEGO Batman, Okami, FF:CC
If I am right on those sure bets, we get to 29. Let's say half of the others make it, that gets us to 34-35.
Toss in some sports titles (Madden, NCAA, etc) and maybe a movie based title or two (Iron Man, Indy 4, etc), and surely some more unnanounced titles (Nintendogs Wii, Red Steel 2, Kid Icarus, Carnival Games 2, etc) and I can easily see us over 40, but not by much as these games are likely to be late releases that won't have as much time to accumulate the totals.
Since coolestguyever claimed 43, and 68soul claimed 44, I'll stake a claim on 42.