It’s doubtful that will end up anywhere else. I think if you want to play it, you’re going to have to snag a Wii U. That’s not a bad thing necessarily. Lots of great games on there that may not come to the Switch.
That said, I suspect the Wii U will ultimately be one of the more collectible systems down the road because the quality of the lineup is rather high, there are many unique games on it that won’t be playable any other way, and the sales were low. People will want to collect it so any system you buy now would retain lots of value IMO.