I'm thinking 15m lifetime sales. Nintendo will want to get a new console out as soon as possible, they've probably already gotten teams working on software for it. 2015 will see a few big titles like Zelda and Metroid but I think that will be it. The new console will probably be out in 2016, maybe 2017. Nintendo knows the WiiU is dead, no need to prolong it's suffering.

I guess the question there is what would be so different about the successive Nintendo console that would allow it to fare any better than the Wii U or GameCube? 

People simply don't want to buy a console for only 2-5 good games per year, that's just the bottom line, it doesn't matter how good of a Mario Kart or Mario or Donkey Kong or Zelda game Nintendo can make especially when all those franchises are now available on the 3DS/future Nintendo portable. 

Nintendo needs to make a move out left field with their next console. Maybe go big into VR tech. They can't compete with a conventional console, they have to do something that will get everyone's attention. 

The simpler approach would be to consolidate with their portables, focus on ease of entry again, with the much-discussed "home dock" being the only real console for the benefit of local multiplayer.

Bridge more into attracting mobile 3rd party support rather than trying to get the same games the 4-1's successors are going to get.

The problem with VR is it's expensive and Sony is already moving on that. Also probably not very kid friendly (hi mom, your 8-year-old son vomited all over your floor after playing Nintendo VR for too long) either. 

No more than 20M

20 million is out of reach but it has a small chance of reaching 15 million before it gets terminated. I believe Nintendo will go multiplatform soon but they still will try to make their own hardware, at least one new home console before they give up.

I don't know at this point... 240 million?

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I forsee a Mario Kart 8 delay to August. Redesign plus rebranding (WiiU becomes Wii2) announcement at E3. Release in august alongide MK8. WiiU goes from being a clunky looking device to looking like an Apple device. Price cut to 250 USD. New 200 mill USD deal with Leo Burnett. Strong and consistent 1st party software from august to december. Revolutionary NFC software/gamepad software that will blow your mind. 

At E3 Nintendo will announce "Operation Extreme Momentum" and it will be glorious.

If they can execute on that, then sure, they can turn it around into doing decent numbers. Will they execute on that? Most likely not. But there is a chance. Believe!

I predict 18 million.