@OP:
The current situation is not rosy, but your minimum prediction is too low:
Ninty, thanks to its classic exclusives, should already have 20M granted, and despite them being extremely casual, and being very pessimistic about them too, we can still think that 5M of Wii users not fans of classic Ninty, but just new Wii stuff, could upgrade to Wii U, and then we can still add another 5M totally new users, so IMVHO 30M should be the minimum lifetime sales.
Also, Ninty, even when having stellar success, always avoids like the plague growing too much and fast and becoming bloated, it prefers temporary HW shortages and periods of sparse SW releases to it, so, as usual, it will be fine even with numbers that would keep MS and Sony in the red.
Stwike him, Centuwion. Stwike him vewy wuffly! (Pontius Pilate, "Life of Brian")
A fart without stink is like a sky without stars.
TGS, Third Grade Shooter: brand new genre invented by Kevin Butler exclusively for Natal WiiToo Kinect. PEW! PEW-PEW-PEW!

