Well I think that's a good idea. People buy Nintendo branded game, rating aside. I don't think they need to be rated M, but if Nintendo supports the new cinematic action or gory action genres (thank you RE4 once again) then that'll get the userbase to like it as well. Seems reasonable actually. Metroid: Other M actually seems like something to attempt that.
However, I question developers who speak like this. Why wait for Nintendo? Why not do it yourself. Shows some initiative and create the "ultimate game" for older more experience gamers and market it as such. And don't forget about the quality part haha. I guess this speaks to Nintendo's dominance as a publisher in the gaming industry but that doesn't mean they aren't the only ones who can do it.
Devs should step up themselves and stop waiting for Nintendo to help them out. Nintendo will help if they think it deserves it (Conduit, Monster Hunter 3 for example).
