Welcome back JL.
Finally a prediction we can agree on again (almost)!!
Actually, I think at this point 1m/month in NA is almost a no-brainer. It's at 700k+ now, production is increasing, Wii Fit is launching and typically a console will sell best in it's third year - which means we should only expect to see sales continue to grow until at least mid '09.
Edit: To clarify I'm predicting an avg 1m per month in NA (not just USA) by mid '09.