It probably would have sold in the range of 30 to 40 million. I think it likely would have needed another name than Wii U, but its possible that the Wii U name could have worked if Nintendo educated consumer through proper marketing. But that would be expensive, when you could just choose a name that is not confusing. Ultimately, I think Nintendo at that time was just not ready for prime time in the HD market. It still does not solve the drought of Nintendo software the Wii U constantly faced. It does not address the issue that Nintendo had a identity crisis since the Wii. Where they became a extreme casual company and then could not find a market or redefine themselves after that (of course they solved this with the Switch). Also questionable if this would have gotten third parties to work with Nintendo.

So I think in this alternative timeline, Nintendo would have had modest success with the system, but still searching for solutions. Which likely would still have lead to a Switch like solution, since 2 systems were just no longer practical.

Switch might've still happened eventually in this situation, but it would probably be half a gen at best in spec upgrades.

Wii U had some specs better than Xbox 360 and PS3, some worse (net lead over them). A Wii U in this What-If would be on par with a PS4. 

The upcoming Nintendo system in real life will be around a PS4 in specs at least if rumors are to be believed, possibly better.

Getting back to my earlier sentence, Nintendo would not cut Wii U off in 2017 in this situation and even by 2019 or so when they release a new system there's no way it would be a Switch with PS5-like specs. 

A hybrid system seemed inevitable, and Nintendo seemed to pick the best time to do it when they could get away with a bump (but not generational leap) from Wii U and a huge leap from New 3DS. 

In that case the Wii U goes onto sell ~60-70m or so units, and Nintendo release a 3ds 2.
There is no Switch.... but a well selling new 3ds (not quite as powerfull as the switch) and a Wii U that sells much better than the Switch did.

I think the switch would be doing really well but in this alternatie universe the switch would actually be upgraded and actually rival the other consoles!

But not my much. Wii U is basically akin to the same gen as the XB360 and PS3, in terms of performance imo.
Its basically just a gen behinde at that point.  Which was a major bummer, near end of the gen cycle, they release a console that was dated in terms of specs.
When people where looking forwards to a new gen, with better stuff, dreaming of the PS4/XB1 ect.

If it instead as ahead of the PS4 and XB1, in terms of launch date, but with simularish hardware...... it would be in a much differnt place than the wii U ended up.

Can't say really, as hardware and games weren't the reason for its failure. The uber casual audience Nintendo captured with the Wii didn't see the point in buying what was perceived to be a $300 Wii peripheral. Just botched marketing to a non-gaming audience who bought their previous system. More power wouldn't have mattered if people thought they're only buying an extension of what they already had.

Hard disagree here if wiiu was aps4 and sold 60 million switches would have still came out on probably 2018 and still did great and probably be the same power wise.

It would probably have sold 8-11 million total, so a little worse. At that point in time Nintendo had no appeal among the core gamer market, besides hardcore Nintendo fans. How would they have marketed the system to people who were already on the PS or Xbox train? They wouldn't be able to. Besides, the system would be more expensive, which would just hurt it more, and the novelty factor would be gone. Parents would still look at 3DS as the better option.
On the positive side, it would probably have more third party support, like with the Gamecube, but it would not have made much difference, it would still not have similar support to the competitors.

The problem with the premise is that it glosses over why the Wii U actually failed so hard, the internal hardware was pretty much the least of it's problems.

1. Name and design way too similar to the Wii, making people think it was just a tablet controller for the latter console
2. Completely botched reveal and marketing. Not only did they go über-casual with the marketing ticking off gamers, there again they didn't mention that it was a new console - or a console at all. This all just reinforced the problem on number 1.
3. The fact that Nintendo let the third party go first and not have a big release title for the console backfired (remember the "unprecedented partnership" with EA?), as it resulted with Nintendo lacking any compelling exclusive at launch. No, ZombiU doesn't count, even at it's best it would only have a reach of 1-2M, while a big launch exclusive should have 10 times that reach. The publishers also shot themselves in the foot by mostly releasing late ports at full price when they were already cheaper on competing consoles instead of new titles, removing any reason to buy the console for their games.
4. The tablet controller. Few publishers, and even Nintendo themselves, really knew what to do with it. And with it's life being so cut short, there hasn't been much experimentation with it either, so who knows what they would have come up with had the console been a success.
5. Only now do we get to the low-power hardware, especially the CPU. It was made in a way so that it would be backwards-compatible with the Wii, but in practice that meant having a 14-year old CPU (the CPU in GameCube, Wii and Wii U is based on the IBM PowerPC 750 from 1997) overclocked and tripled. Even with the extra cores and clock speed over the Wii, that CPU was extremely slow due to it's old architecture - too slow for many contemporary games to run smoothly without tinkering. Publishers were used to the reverse problem, where they had a tiny GPU that needed support from the CPU to run smoothly, so direct ports would run pretty badly on the Wii U. Not that the GPU of the Wii U was much more powerful than the one in the 360, they were actually more or less on par, it's big advantage here was the much larger VRAM of 2GB (which Nintendo then botched with a slow DDR3 interface), which allowed for more detailed textures and less loading from the slow RAM, but that's about it.

Now, had numbers 1-3 worked out, number 4 or 5 wouldn't have been a problem. Low-powered hardware in itself ain't a problem, just look at both it's predecessor or it's successor. Or at the original Gameboy beating the Game Gear, PC Engine GT and Lynx combined handily. Or the DS curbstomping the PSP. Or the PS2 trashing the much more powerful Xbox and Gamecube. It's the other factors around the console which had a much bigger impact on why the Wii U failed than the hardware itself, though the latter certainly wasn't helping matters either.

For the record, I'm not proposing that this is what Nintendo should have done instead of the historical Wii U, or that this would have fixed their problems.
It's just a hypothetical.