It's going to top 10M in CY 2013. Wii U should have atleast one AAA title to boost the sales before the end of march; Wii Fit U.
Will that boost sales? I can't see people feeling the need to upgrade wii fit to wii u fit. It's not like you bought Wii Fit for the graphics, so why upgrade? This is the major downside nintendo never considered when they focused on the casual audience; getting them to upgrade when you are no longer the "in" gadget is incredibly difficult.