There's talk of it based on something a Brazilian cinema chain said, and the talk of Bowser Jr alongside him makes us think it may be slightly more credible than before:
gamingreinvented.com
Could this be the push to relevance the character and his games need again?

Could Wario & Bowser Jr Appear in the Mario Galaxy Movie?
According to rumours going around at the moment it seems possible, especially given two of them confirm the latter…
Could this be the push to relevance the character and his games need again?