After extracting himself from a jam, the flat one may get some additional definition.
http://www.nintendoworldreport.com/rumor/41829/paper-mario-wii-u-title-in-testing
Intelligent Systems has been working on a Paper Mario title for the Wii U and the game is in testing according to several sources close to Nintendo.
It isn’t immediately clear if the title is a remake of an existing title or a brand new game. Intelligent Systems was rumored to be hiring staff last spring and mentioning a new Paper Mario game was in development. The timeline matches the time the Japanese version of Fire Emblem Fates would be wrapping development.
The project is definitely slated to be a Wii U game, and other platforms are not being talked about as far as we know.
If it's true, I doubt it's a new Paper Mario. Not with the Wii U at death's door. It's probably just Thousand Year Door HD: something they can just **** out in a few months.
Or they just use the Thousand Year Door's assets and core engine to make a Wii U sequel. Everyone felt that was the best for the series. I'd love to see a direct sequel because Nintendo tends to knock those out of the park, especially when they are in the twilight of a console's life and get really creative with them (Mario Galaxy 2, Pikmin 2, Radiant Dawn, Majora's Mask).