Do I want a gritty wuboot of Mario, where he and Bowswer exchange "F**k you!" back and forth? No, thanks.

If by look mature you mean how the games might have a more realistic looking world with mature content and dialogue? For certain games and series sure, for others, no.

Fire Emblem, Advance Wars Days of Ruin, Metroid, X, etc, all look like they're in a more mature world. The worlds in these games seem more realistic and have more violence and more mature dialogue. Some Zelda games even have a mix of this style with a somewhat realistic looking but cartoony world, although family friendly dialogue. Hyrule Warriors seems like the most mature of the Zelda games with heavy sexualization to the female characters.

People need to get over this. Being available for ALL AGES! does not mean that it can't appeal to older audiences. Games are mature if they're meant to be, and honestly there are too many of those. Franchises, hell, entire companies are destroyed because people think they need to change, but it just loses the appeal.

This is the company which convinced the ESRB to give Majora's Mask an E rating. Pamela's father is a zombie locked in a wardrobe and the game gets an E.

Nintendo's problem isn't that they can't make compelling mature content--they most definitely can, and they can keep it remarkably clean, to boot--but that they don't.

Personally, I would love to see a relatively hard Zelda game where Link is in his mid-50s and can't run and jump like he used to. Nintendo could make that work very well. They're not going to because it would likely hurt sales in they 8-15 year old demographic even if it had an E rating.

Honestly, no.

I'd be interested in them if they innovated like they used to.

Every day I see people hyped up for the "new" Smash Bros coming out in 2 1/2 hours, and the new Link game. I saw it for the "new" Mario Kart and the "new" Pikmin and the "new" Super Mario Bros. and the "New" Super Mario 3D World and the "new" Pokemon.

I got so sick and tired of seeing these same games coming out.

I played Nintendo since the 64, and what brought me in were the new and exciting games that they were making. Pokemon Yellow was my very first Nintendo video game, and I remember loving every second of it because it was something I'd never experienced before. Remember how cool Paper Mario and Luigi's Mansion were the very first time? Remember how jaw-dropping Super Mario 64 was and how exciting and innovative Rare was? Remember the non-stop party fun from the first WarioWare games? Remember how each step Nintendo made felt like a massive leap of innovation spanning generations before we were supposed to get it?

Yeah, well now it's the same stuff their competitors do. Make an old IP sellable with a new paint job, a couple of characters and some new maps.

And people let them get away with it because it isn't a "yearly" thing like COD or AC.

I want innovation from Nintendo.

*Looks at Splatoon*

BETTER THAN THAT! If I wanted to shoot paint at people I'd just play Paintball!

I want the Nintendo that stole my heart by making exciting and captivating games that broke ground on new ideas, not the Nintendo that shoves hardware gimmicks in your face and claims that the innovation in software will soon follow.

Cause all I've seen this year are the games I've been playing since 1995. 

Inspire me again, Nintendo.

Then I'll buy your products with a smile on my face.

It gets harder to wow people the longer they game. Because everything has been seen and tried in some fashion. Also, half the time people don't buy anything new. What happend with W101? That didn't need to bomb. Tomodaichi Life is new. Is that your cup of tea though?

I'd buy a more mature Metroid First-person shooter game. For many reasons, If you know what I mean. ;)

Some, likely, and probably not.

If some of their games were more than superficially mature, as described in your post (which is either a joke or a textbook example of how not to go about this), then they could certainly attract some interest from outside of their current demographic. Their "old fanbase" wouldn't have much reason to complain as long as it was done well. And no, they wouldn't shake their reputation; that's almost entirely a problem of branding, which is a completely different issue.

The Mario thing you wrote sounds more like a Wario game.

I think Wario Ware would be the perfect franchise to turn M rated.