even your lowest guesstamate for wiiu is to high, 25 is as high as it can hope to get to before they pull the plug.
its been out long enough to see where its going, things wont be getting better. as comp gets going ill only struggle more.
There are probably two factors contributing to the discrepancy between the given estimates and the numbers in your mind.
1) Most people focus on short term.
a) The vast majority of Nintendo First Part Titles are not even out yet; once they're released, we'll see a gradual shift.
b) Most people don't even know that a new Wii exists. Nintendo had the worst possible media awareness of a new gen machine. With the advent of the true next gen machines, there will be higher awareness towards WiiU as well.
c) WiiU will always be the cheapest console, and once it reaches $199, it will be a no brainer buy, regardless of its specs or third party support.
2) Most people misunderstand the estimates, which assume a 7 year cycle for all consoles. However, wiiU is likely to have a shorter lifespan, so if you assume, it will live 5 years for example, the total sales will be around 5/7 of the given estimates.
Regional Analysis (only MS and Sony Consoles)
Europe => XB1 : 23-24 % vs PS4 : 76-77%
N. America => XB1 : 49-52% vs PS4 : 48-51%
Global => XB1 : 32-34% vs PS4 : 66-68%