An M rated Zelda would be interesting but not unnescarry.
There are two that would benefit from an M rating. I think Metroid would work very well with a darker tone. It's already more mature in context than a lot of other M rated games and even at times feels more violent with the dismemberment and gore. We're often exposed to open wounds that show the inside of various enemies and their slimy guts sometimes slide down our visors after we blast them. So yes, there are a lot of things that can be easily done to make Metroid M rated. It doesn't need to be extreme but rather done to set a tone. It would be interesting if this would widen it's appeal to other audiences. I don't think it would harm Nintendo to try this at least once with this franchise.
The other series that would benefit with an M rating is the Fire Emblem series. Without a doubt the context is often mature with sexual tensions and themes. It would not be hard to make an entry more suited for the Game of Thrones audience. After all it's not like that series feels like it doesn't take a few cues from Fire Emblem. This game could hit another level of gamer mainstream if took a swing to realism. The violence, the sex, the politics, it's all there in Fire Emblem. It always was. It's just hinged and caged from your eyes as it all occurs off screen giving us enough context to fill it in ourselves within our head. Fire Emblem unhinged could be a serious potential system seller. While some fans love the current style of the series, it wouldn't harm to try expanding the horizon and see the consumer reaction of such a gamble with the potential of a seriously large pay off. The ingredients are already there within the formula.
As for an M-Rate Xenoblade... sure it would work. Though how will it benefit and enrich the overall experience?
Oh and M rated Mario... not going to happen. There isn't a pay off for that and it would be nothing more than a cult classic that will result in the worst press against Nintendo's reputation. Tonight on Fox News.... On the bright side maybe this guy slip up and pop his head again for a fresh batch of internet memes!
