You know, I think obscure Mario characters have a good future:
K. Rool in Smash was HUGE. It'll be a moment in Nintendo history which cannot be overstated, that probably lit something or other inside Nintendo's walls, considering that a year or two after K. Rool came aboard, mobile Mario spin-offs started embracing lesser known characters - we saw Baby Wario from Yoshi's Island DS get his PHD, King Bob-Omb; Nabbit; and Dixie Kong took to the tracks, Goomba got its third playable role, even the dolphins got in on the fun.
Now, you could mention the Origami King interviews, but considering how long game development took that probably started development around the time of K. Rool's reveal, before they knew there was a demand for classic characters to come back. Remember that Sakurai said he had no clue fans wanted K. Rool until the ballot.