NATAL recognizes up to 4 individuals at once, so 4 players - 1 NATAL.
GS is top of the line in the investment world so their projections have to be taken very very seriously, although they could still be wrong of course.
People seem to think this is aimed at the Wii. It probably is aimed at Wii HD instead. This way 360 can keep chugging along and capture the HD upgraders.