Yeah, I doubt Wii U prices are going to dip very much. For used units, maybe a bit cheaper initially since some people may sell their Wii U stuff in order to grab a Switch. Retailers might cut the price for new units, but not dramatically (they want profits too). Wii U production has stopped iirc, and I know a lot of game collectors are eyeing the Wii U. Once they start buying things up, supply dries up with it, demand increases, so that's another factor to consider.
Personally, I'll pass on the entire Wii U library. I was only interested in Star Fox, Super Mario 3D World, Xenoblade Chronicles X, and Mario Kart 8. MK8 is coming to the Switch. Maybe the others will come eventually. I wouldn't expect Nintendo to do that right away, because that would basically be a big "f**k you" to current Wii U owners. If not, I can deal with missing out on those 3 games. Can't wait for Xenoblade Chronicles 2
Personally, I'll pass on the entire Wii U library. I was only interested in Star Fox, Super Mario 3D World, Xenoblade Chronicles X, and Mario Kart 8. MK8 is coming to the Switch. Maybe the others will come eventually. I wouldn't expect Nintendo to do that right away, because that would basically be a big "f**k you" to current Wii U owners. If not, I can deal with missing out on those 3 games. Can't wait for Xenoblade Chronicles 2