How long do you suppose they'd do it in? Worth remembering both games are not written on the same architecture as the Switch (PowerPC vs ARM), and would both need a little work done to remove any Wii U features (e.g., the gamepad, Miiverse, etc. - not suggesting they'd replace them with anything though).
6 months seems like a solid estimate for that work, given I think it'd have to be outsourced. Perhaps 4 at a push. Either way, I'd say it could be possible, just whether Nintendo would want to fund that work if they haven't already by now.