Assuming Nintendo keeps releasing a new console every 5-6 years, I would also say that it will end up below 20m.
IMO Nintendo has only 2 more chances to really turn things around.
1) Mario Kart 8
Didn't help the GC, but due to the popularity of MKWii it might convince a lot of them to buy the console.
2) Wii Sports 2 (or 3 if you count Resort as 2) or similar casual game
Something to attract the casual crowd. Wii Fit U didn't help, Just Dance 4/2014 didn't either and a simple sequel of Wii Sports might as well be not enough. The chance of creating another hit like that is not very probable unfortunately.







