Their games are huge. I don't know what you are on about. Mario still sells at an immense attach rate many series wish they had. Zelda was always a more moderate sucess, but still very sucessful.
Mario maker, smash, splatoon have all had quite a favorable acceptance amongst all audiences.
I really have no idea where this is coming from. Its not the first thread i've seen lately with such outlandish notions.
Oh... do you mean how will they target a mature audience? Well... i'm not sure they want to. But bayonetta and devil's third were efforts in that regard.