I voted 40-50 but think it will be closer to 40.

I voted, but not based on your 'factors', as i don't agree with your opinions.

30-40 million.

In 2015 they will make a new system with better specs than PS4. Wii U will become the cheapman/casual system and sell helthily for a year or two more.

This is very hard to guess given the current situation of the Wii U i say around 20-30m lifetime is very realistic,but you can never know i mean just look at the Ps3! such a horrible start and now looks like it could even finish first lol!

I voted 40-50 million, but I can't be certain. Like I say with the Vita, I predict it'll sell somewhere inbetween 10 and 90 million.

Amazing.  I made that prediction a year ago.   Thought I was the only one to think WiiU will have a short lifespan, and be replaced by a true 8th gen console.

Not replaced, more like GBA to DS. Nintendo will support both Wii U and  new system as long as possible.

Best case scenario-Wii level sales(100 million)
Worst case scenario-N64/GC level sales(20-30 million)
My prediction-NES/SNES level sales(50-60 million)

While I agree WiiU will still be sold, I disagree it'll be supported.  Nintendo is terrible at supporting older systems. Both GC and Wii had game droughts for their last years.  Heck, Nintendo can't even effectively support two platforms anymore with development times, let alone three.  

Plus Nintendo has merged their mobile and console hardware teams so the new console would likely replace both 3DS and WiiU and probably be a WiiU-esque device that'll play on your TV and on the road (but will need to be more than that, because such a device is already available (Galaxy S4) so it'll have to be at least as powerful as PS4/720 as well).

If anything 3DS will continue to be supported, but not WiiU.  If Nintendo does release a new system in 2015, (I said 2016) 2014 would be the last year for any main games.

80-90 mil.