That tells me that you think price to performance/features wasn't a large factor in sales. "We might have seen 20-25 million range.", isn't a very confident statement. That's about 5-10 million more units sold.
I disagree. I think it would have done 35-40 million had the price been $250 instead of $350, for the 32 GB model of the Wii U. It still would have been a console with sad sales. Just XB1 levels of sadness. Switch probably wouldn't have released in 2017 with sales like that so it would have an extra year or two to get those kind of sales up. So something like 30-35 million by 2017, and another 2-3 million or so in 2018 and 2019 each.
Why? Because the software for the Wii U just wasn't there. It had 2 years of good games bookended by two massive droughts.
What if Nintendo had released the Wii U as a machine rivaling the power of the base model PS4, for $400? How much better do you think it would have sold then?
Please answer before viewing my own opinion on it below...
I think a PS4 level Wii U, with a 32 GB HDD, and Wiimote/Nunchuck controllers (no Gamepad/Tablet included) would have sold 20-25 million. In other words, I think it would have been better for Nintendo to release an underpowered Wii U at $250 than bother trying to make a Gamecube 2.0!
I still think it would have failed but it would have sold more than the meager 13 million. Because many gamers would have seen it as a future proof machine.
Third party support wouldn't have been as dreadful, but the issue remains as killer exclusives would still have been a problem. BotW didn't see the light of day until 2017. We would be seeing 30 million units here. An under powered Wii U at 250 would still sell less than 30 mill...no Xbox One numbers. Some said at 2010 release...I can actually see the cheaper, HD Wii U selling better then.