Between Mario Maker Wii U, 3DS, and Super Mario Run, it'd be impossible for Nintendo to sell a NSMB in the same vain as the previous 4. Maybe that confirms the end of the series?
I'm pretty sure it's been all but confirmed dead. I'm pretty sure that Nintendo said whatever next steps a console or handheld Mario will be taking will tread new ground some time recently, Either way I sincerely doubt the next AAA Mario title will have a three-dimensional Mario model running across flat, ugly, repeated tilesets. If they want people to get interested in Mario and Nintendo again, they're gonna have to promise much more than just another NSMB game. They were cool at the time but look insanely dated today, especially at $40-$60 a pop.