You said Nintendo.  You didn't say only home console.  

Google the other 2.  Rockstars most violent game ever was on a Nintendo console.

So you claim that it would sell better on Vita than on Wii U on the basis that they haven't even tested the Nintendo home console market? Kind of like going "Since I've never won a game of tennis, I should never try to play tennis in the first place".

And you claim that GTA belongs to PlayStation. If that were true, wouldn't Chinatown Wars have performed better on PSP than on DS? After all, the PSP was clearly the technically better system, and the market was clearly Playstation users. So on the basis of your assertion, Chinatown Wars PSP should have thrashed the DS version. Remind me - what happened? Or are you going to suggest that all those PS2/PS3 gamers were playing Chinatown Wars on DS rather than PSP because magic?

It seems to me that a market that they've never tested is an obvious one to test. Releasing one major GTA title would be a sensible way to test the market. And even in the worst case scenario, they'd make back the excess cost, because GTA is pretty much guaranteed to sell well, and porting wouldn't be difficult.

I always laugh when I see people invoke terms like "target group" or "demographics" (yes, I know you didn't say this one, I'm referring to it as being like the one you said), because it shows a complete lack of understanding of business, and especially of what it was that made the Wii so successful. Recall that "Blue Ocean Strategy" that Iwata was always talking about? It's the concept that, when you start serving a section of the market that hasn't been served, you do very well (obviously, I'm very much simplifying). It's also the only way to grow the industry - by serving customers that otherwise haven't been served.

Nope. Nintendo has kids as main target group. Sony and Microsoft has adults/teens as main target group.
Why should it boost Nintendo hardware? 

Nope. Nintendo has kids as main target group. Sony and Microsoft has adults/teens as main target group.
Why should it boost Nintendo hardware? 

That might have been the stupidest thing I have read today. Porting GTA V to the PS4 and XBO makes less sense than it would have to the Wii U? GTA V's target audience is completely on those systems unlike the Wii U.

GTAV was release one year before for ps360. rereleasing on ps4 and x1 is redundant in terms of audience. Besides, it's terribly inaccurate to say the target audience is COMPLETELY on those systems and not on wii u.

Alright a large majority of their target audience is on PS4/XBO. Is that accurate enough? It doesn't change the fact that GTA V on the Wii U wouldn't be anything special in terms of sales, software or hardware. As for porting to those two systems, they were already porting it to PC so it makes complete sense that they'd port it to the newer consoles with some extra additions.