I think they are still big, just not as relevant in kids and some peoples everyday life like they used to be. Mario Kart 8 has had really good sales despite its userbase, Same with super mario maker. The love for Mario games definetly still exist. Legend Of Zelda i think is becoming bigger than ever. We get constantly new Zelda games and things like that, with spin-off titles, remakes and so on and so forth. I think if the NX has a big userbase we will maybe see Zelda titles getting big sales. Also Zelda remakes/remasters on the 3DS sell really good.
What i want Nintendo to do though is make Metroid more relevant than ever before, and not the way like Federation Force, (it still might be a good game, but not what will attract people to the metroid franchise). Nintendo really needs to maybe remake or just make a brand new full blown awsome Metroid game, with different exotic planets, haunting atmossphere and the feel and mood like the Metroid Prime trilogy blended in with Super Metroid
