Nintendo really doesn't try to rigidly adhere to a specific game genre when designing a game anyway, they just kinda make each game work however they feel is appropriate. (We also have a very flawed definition for the word "genre" in this industry anyway, generally it is supposed to define narrative tropes and structure.)
I would not be opposed this Diablo-ish action dungeon crawler the OP suggested, however they would have to give it a unique flair to make it appeal to me.