Inafune talks about Indie game and some Mighty No. 9 during the lecture at the Unreal Fest 2015 Yokohama Event.
I only glanced through it, more info from Gamespark, here are some rough translation I made for GAF:
-"Mighty No. 9 absolutely will not be delayed."
-"One of the reason of the delay is because of the numbers of platform."
-"How to make the impossible possible like Mega Man."
-"Cannot say it's a complete success yet since it still haven't been released."
-"The game needs to sell a lot of copies and many users playing it."
-"Sequel is planned if it were successful."