Definitely not happening. Nintendo is running away from the Wii U as fast as possible.
And no, hackers are not going to add it somehow.
Only way is to download the content into your Switch and place it on top of the Wii U
Holy crap! that's amazing. Not sure how to install this.
how you install it would depend on how it's being delivered. it could be a wup install or just replace certain files via ftp.