50 mil. lifetime is a bit much...

I think the wii u will reach N64 numbers eventually (at best). Which is actually pretty good. It might still be a commercial success

Seeing as how I believe that the Wii U's main problem is lack of basic appeal, no amount of good decisions, price cuts, software or advertising will help it achieve great sales, or even good sales. The whole console simply lacks aim and planning, and that's a fault that lies in the core design of the product itself, there are no external factors causing the vast majority of these woes.

Maximum under the best circumstance; 30 million. Likely lifetime at this point; 25-20 million.

The main problem is the system doesn't have a whole lot going for it other than Nintendo franchises which I think still only gets you between 18-29 million. The Wii brought in other consumers with the novelty of motion gaming, but that has been mined dry too, so Wii Sports/Fit/Party are not moving the needle on Wii U sales at all.

The other issue with "Nintendo franchises" is the ones that actually are capable of selling hardware have kinda become fewer in number as Nintendo chased casuals the last 5-6 years. 

It used to be in the SNES/N64 days, something like Star Fox or Wave Race or Killer Instinct or F-Zero could be 1-3+ million sellers, but today it's basically become the Mario platformers + Mario Kart + Smash Bros. + Zelda (and even Zelda, if its not a realistic Zelda it's not a system mover). Then you kinda have DKC which is a decent seller still (I think) but probably redudant in the audience with Mario already there. 

Everything else really is not moving systems (as much as I like X and Bayonetta 2, those are probably going to sell as well as Pikmin 3 being optimistic). 

I'm surprised Wii U has sold as bad as it has. I will probably get all 3 systems eventually.

As a primary console I think majority will pick from PS4/XB1, but some minorities will pick the Wii U, and some will pick PS4/XB1 plus a Wii U.
This puts the Wii U's role in range of GameCube.

My prediction is 20 to 30M lifetime for Wii U.  I think it will remain a secondary choice to PS4/XB1.  20M is a lower bound based on GameCube sales, but 30M an upper bound based on a slightly expanded market for Nintendo following Wii.

Somewhere between 4.5 and 400 million

The WII U will achieve 30 million at best under very optimistic circumstances but under realistic circumstances it will achieve somewhere around 15-20 million.

It'll sell around 20 million no matter what. Nintendo will replace the console in the fall of 2017.

I suspect this generation is going to go on for quite a while. Plus there will be the dawning realization that with all the tablets and smartphones out there, that you can't expect people to just keep dropping the same dollar amounts the same way as in the past.

Gamestop just stopped dealing with PS2 this year. The prior generation of consoles from Wii to PS3 have had all manner of services and games available to keep most people using them for another half dozen years all for lest cost than the current generation which with DLC, microtransactions and other nonsense are trying to push the cost even higher. Plus there are tablets and smartphones galore all competing for those eyeballs.

This transition is going to be like when we went from DVD to Blue-ray. There was no real winner. $25 upconverting DVD players, streaming and Redbox all combined to make a much smaller market for Blue-ray. It will likely be the past disc based standard and will last for as long as it needs to last while other solutions swamp it on all sides.

Wii U is doing fine. This generation is going to have to go on for 10 years, avoid losing any huge money up front, figure out how to sell content across a number of price points, and the winner will be the company that profits, not the company that moves the most boxes.

This generation may go on for a while, that doesn't mean the Wii U will though. The market has the final say and right now they're saying "not interested" in the entire Wii U concept. 

THere will be droughts period. THey are nto getting the backing of 3rd party games so that is inevitable. Ninty is not going to be able to make up the number. i say 35mil