Capital letters?

mario u was a 2d side scroller, wasn't meant to sell systems.

people bought ps360 just for playing gtav.
why wouldnt they buy a wii u?
at moment, lots of 3rd parties were on wii u, so, it wouldnt be the one game for that audience.

With origin on wii U, and if that garanties all EA games on wii U and great online.

I think they could get some of this audience , just the enough for still getting 3rd party games.

It would still be a failure.

In my opinion, the reason that console failed is because of the tablet control. A more powerful console that still used the Wiimote as its primary controller would have been more successful.

Selling like dreamcast if EA backout later on wiiu life about the online support. If not, would sell like the gamecube.

Both thoose cases would be a improvment on what we have today, actually D:

It was and kinda did (just not as many as Nintendo had hoped). 2D Mario is far bigger than 3D Mario, just look at the sales for the two series. 

According to what?  Hindsight?  New Super Mario, a game that had sold over 25m the previous generation (twice), and led to the Wii having the largest sales month in the US ever wasn't supposed to sell systems?

I also really don't get this narrative that has been forming around the GTA rumor.  Why exactly would GTA provide some reversal of fortunes for Wii U sales while other major multiplats barely moved the needle.  Call of Duty sells terribly, but GTA would have been huge?  Why?

Also, I doubt a Wii U release at launch would have even been practical, and definitely not a priority (well obviously since they didn't make one).  GTAV already had been delayed once, online wasn't finished at launch, and heists were just recently added in a year and a half later.

Fifa 13 sold horribly. Third party games in general sell horribly on the Wii U, which is why GTA5 wouldn't change anything either. And a system seller at launch would have sped up the sales for a while, but we'd still have that drought.

So basically, almost nothing changes.

That is true, it did have them. However, you have not taken into account that most people who bought the Wii U at launch most likely had a PS3 or Xbox 360. With that in mind, they most likely already had Mass Effect 3 and CoD Ghosts/Black ops II. Why would they buy it on the Wii U? They wouldn't.