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).
Radiant Dawn wasn't a late era release, it was a early era release. It was a Wii game released 3 months after the system launched. MM got panned critically and in sales, it was only like 2 or 3 years ago that it suddenly started getting a lot of love.
With all indications that NX won't come out til next year (no way is it coming out in 2016, and no credible source thinks it will either), a new Paper Mario game would help be a great holdover for Wii U. Hell, i'd even be happy if they started finally selling GameCube games on the eShop so I could download Thousand-Year Door.