One of the problems Nintendo has is they have a tendancy to get too cartoony, which actually has the opposite effect of what they think it does ... it alienates adults from their games, and kids don't really care one way or another, they'll play just about anything. 

Like Splatoon is probably my second most wanted game for the year (after Mario Maker), but this looks like something from a Nickeldeon kids show for 8 year olds, and the main characters being kids full out probably is going to prevent a lot of teenagers/adults from ever touching the game:

And I mean I think you can do an art style that is cartoony, yet still appeals to teens and adults, games like Borderlands pull it off:

Whereas this ...

I mean this, while it has charm out the wazoo does look like something aimed not only at kids, but pre-school kids at that. Ditto for this:

Even during the Wii era I think they found more success but turning down the cartoony-ish ... the Mii/Wii Sports/Wii Fit/Brain Training asthetic while not overly realistic wasn't like Mario Sports or Mario's Math Studio or something ... the more "neutral" style allowed adults to play those games without feeling like they were playing something aimed at kids. 

I know people will say "yeah but adults should just man up and play that anyway, c'mon", but most adults don't feel that way. Part of growing up is indeed part of having your tastes change. When I was 9-years-old, about 90% of the TV/movies I watched were animated. Today that's maybe 5%, sure I'll watch a Pixar movie ... but that's like maybe once a year tops. 

Mainstream gamers? If Nintendo dont aim for them then how will they survive? And to attract mainstream gamers you dont need COD. As OP said you need something cooler that attracts mainstream. Splatoon reveal was cool. So they need something like these. Or something like in Zelda U big.

Nintendo is cool:

Here is a few more "cool looking" titles that should appeal to an older audience, and are exclusive.

Yes indeed.

the amount of PRIMARY SCHOOL children that don't own a Nintendo console and instead a ps/xb because N ain't cool here is incredibly astonishing.

It's a thing. I went through it only a few years ago lol. :p

I share your view. It's funny, as I'm getting older (26) the term "cool" has been redefined for me to be "whatever i like", and i like Nintendo.

I literally just said that they should aim for them at times. I also never mentioned COD.

Please read and don't make assumptions.

Exactly. 'Cool' is entirely subjective. For instance, I don't find realistic shooters to be cool anymore but millions of people do. I think platformers are really cool, and millions of people don't. 

They can if actually tried. Whether targeting a child or adult audience people are sold on concepts. As much I love a gameplay trailer Splatoon's audience be reached pretty well with a "cool" CG action trailer. This doesn't apply to all games but I think Splatoon fits the bill.

You can't be cool if you try to be cool.. either you are or you are not.