If I bought a Switch I wouldn't be interested in re-buying wii u ports like mk8 on Switch as I still have a wii u and games are expensive but I may not be typical with that view. However as many have already mentioned the wii u install base is low so for anyone who didn't have a wii u but buys a Switch those games will be new to them. I would still think sales wise they would be in a mid position between Switch exclusive games from Nintendo and third party games.