An under powered Wii U, without a killer exclusive in 2012 sells about 20-25 million if cheap I am talking 199.99 cheap. A PS4 like machine in 2012 should sell more than that. some of the big third party games would have arrived in better shape than in the 360 and PS3. We are talking about a real 1080p machine (which was a big selling point then) capable of running MGSV, GTA etc. Ports which it might have had.
I can't see it doing much worse than Xbox one which also lacked great exclusives. So for arguments sake with third party support based on the console being competent enough to compete with the PS4 I can see it reaching the 30-35 mill threshold. No where near as successful as the hybrid Switch is/will be but not near the disaster it ( the WiiU) actually was.
Let me take you through what I see happening had Nintendo released a $400 PS4 rivaling Wii U.
The console launches in 2012, but doesn't have a launch title at all. NSMBU is still being worked on because they now have to get it up to PS4 quality graphics. NSMBU finally launches in May 2013. Pikmin 3 and 3D World are also delayed by 6-8 months for the same reason. Ditto for any 2014 Wii U exclusives.
Dragon Age Inquisition, Shadow of Mordor, GTAV, Diablo 3, DMC, Bioshock Infinite, Tomb Raider, etc. all skip the powered up Wii U leaving it to languish with almost no games for all of 2012, 2013, and 2014. "But how do you know these games would have skipped a powered up Wii U?" Because they were all on PS3, and skipped the regular Wii U.
To top it off a powered up Wii U likely would have still been 3rd place in the horsepower rankings because it launched a year earlier.
So here we are summer of 2014 and this PS4 rivaling Wii U has NSMBU, 3D World, Pikmin 3, and that's it. DKC, Mario Kart, and Bayonetta have all been delayed to the holidays. Most of the 3rd party games just outright ignored it. Why? Because making these games for a Nintendo console was never planned. Just like how 3rd parties got caught with their pants down from the Switch's success and took a couple years to fully support the system, this version of Wii U would have caught devs off guard as well. Except it wouldn't have had good sales like the Switch. It would have had bad sales. Worse than the regular Wii U. Because it would have had even less games than the regular Wii U! It would have been even more of a dumpsterfire than the regular Wii U!