Nintendo has become stale in the character department and haven’t really come up with anything new in quite some time. That being said, Miyamoto has commented that there is a good possibility that their will be some new characters incoming. He said this in an interview with the Guardian:
I donâ€™t have a big list of ideas I want to realise. I usually come up with new ideas while I am working on other games. That said, thereâ€™s a strong possibility we will introduce some new characters to the scene soon.
Recently Nintendo reported their first annual loss in 30 years recently and they definitely need to step up their game. This is the kind of thinking that is going help Nintendo make a come back. Mario can’t hold the pillars of Nintendo up by himself forever, he needs help. Nintendo might also want to think about bringing back other characters like Samus Aran and Fox McCloud (Star Fox 64).
Source: Nintendo Universe