I'm of the opinion that neither will be as big as the wiimote, balance board or M+.
I seem to be in the minority that thinks SoMo will fare better than Natal.
SoMo has a pointer. Even if the motion side of things fails hard it can still rely on better aiming controls for any shooter. IMO this would automatically make any 360/PS3 shooter superior on the PS3.
The wand/nunchuk is a proven concept. A 'controller free' solution to a non-existant problem is a punt.
Nov 2016 - NES outsells PS1 (JP)
Don't Play Stationary 4 ever. Switch!