Im not japanese, just live here with my wife :P

I don't think the right way to gain consumer trust is to have severe game draughts due to slow software output, keeping the price too high and refusing to lower it (they would likely start losing money on hardware again though), slow OS, very poor 3rd party support, tiny storage and poor online. The Wii U has not maintained goodwill, even with most Nintendo fans, these forums show as much. It has been a disappointment across the board and is a good show on how not to gain consumer trust.

SEGA was in an entirely different position; they had a single handheld system that did terribly on the market and there was no way of heading for mobile development back then as a source of extra income, their Arcade business had also taken massive hits as home consoles took more and more marketshare. SEGA lost money for five consecutive fiscal years and executed two consoles in a row and then went 3rd party; they had two home consoles pulled from the market in only about 3 years each, Nintendo pulling the plug on the Wii U after 4 years (in 2016) would hardly be the same. They mostly don't support their consoles beyond 5 years at any rate.
This whole notion that Nintendo would "SEGA themselves" if they cut the Wii U is simply not rooted in reality and the situations are very different.

"Whats worse? Taking a few software development losses or not beeing able to sell your next system?"

To me, the only thing they're accomplishing by clinging to the Wii U is fading into obscurity; ensuring that both their current and next console won't sell. If they wait until the Wii U sells even less than it has at its worst; it will be too late and no one will care that they release a new one as they will have no known presence on the home console market.

Their plan of having 3rd parties "submit to" their platforms is a bad one though; I don't think it will work as most developers are managing fine without releasing games for Nintendo's home consoles. While they may see Japan as the most important, and perhaps you as well, I see this as their major problem; they are too traditional and rigidly Japanese in their thinking and they have to focus on western markets more, this is where almost every gaming trend comes from today and this is where the majority of console hardware and software sales come from as well.
AAA publishers are indeed spreading terrible practices, and I'm not saying that Nintendo should jump on these, not at all (although; they have started to move more and more in this direction themselves lately).
The problem with protecting their family friendly image is that families largely don't care about them any longer; what sense is there in trying to cushion the impressions you make on an audience that has moved on to other platforms?
What I'm getting from your post is that Nintendo will and should continue to press for the same old agenda of forcing the market to adapt to them rather than the other way around; this is exactly the attitude that has caused all their problems lately and it must be discarded if they want to remain relevant.

Sony lost a lot of exclusive support in the 7th gen due to their mistakes but they have regained much of it by making good choices with the PS4. Winning two generations in a row is not a prerequisite for getting support, the PS4 is living proof of this. I'm not suggesting they fight an uphill battle; I'm suggesting they stop building their consoles at the bottom of the hill, like they've done for about 20 years now, they have wilfully alienated themselves from 3rd parties by making strange and selfish choices while MS and Sony have created more open and friendly developer environments and have gained good support as a result of this. Nintendo can't sit around twiddling their thumbs, waiting for everyone to realize who and what they are; they need to stand up and make themselves visible and they need to swallow old pride from the 80's and 90's and start reading and reacting instead of dictating and bypassing.

I am not suggesting they appeal solely to Sony and MS' audience; no where have I said that. What I have said is that they need a console with a clear aim, like the Wii had, the Wii U is all over the place and has a split personality. Which market to aim for is up to them, with hardware synergies through more adapted handhelds, mobile games and a smarter, more poised home console, there are possibilities for them, simply letting things grind the way they have been can prove to be their downfall in the end.
I never said they should focus on "mature" gamers, that was your idea and interpretation of my words but I never wrote that; it is all about a proper aim at an actual demographic.

"Rushing into that race would only lead Nintendo to big losses in earnings and consumer trust. They simply dont have the arguments to fight that head-on battle you think they should go for."

Once again; this is your idea and not mine, I'm not saying they should go for Sony and MS' marketshare, my main idea is that Nintendo need to learn how to read and adapt to markets, they need to have better aim with their products.
As for big losses in earnings; look no further than their last 2-3 years, they have lost plenty of money and launched two consoles in a row that took losses on each unit sold from the beginning. They won't survive on the scraps from the Wii U and even the 3DS isn't a huge cashcow like the DS was and is likely headed for a really, really challenging 2016 with low hardware and software sales.
There is no money to be had from forcing the Wii U to stay, and the consumer trust is at an all-time low, because of the Wii U. They need to get rid of it, and they need to do it quickly before everyone turns their backs on them, these very forums show a large numbers of die-hard Nintendo fans who show and speak nothing but displeasure with the Wii U and Nintendo's direction in the 8th gen, one can imagine how bad it could get should they press on with this foolishness.
This fabled consumer trust is not theirs to lose; it is already gone and they need a way of regaining it, the Wii U is quite simply not up to the task and I think that should be clear as day by now.

Lucky you. i wish I lived there. i love the culture and that they are strange.

So having a PS4, its better to get a WiiU than a XB1...

Of course, is just that the WiiU is still too expensive for the library it has.

Not Nintendo consoles, never did unless you're talking about 25 years ago.