And I bet there are porting studios that'd gladly port this to those platforms given the opportunity.
I could easily see Curve Digital, BitWorks and Just Add Water could be great fits for possible porting houses for Hyper Light Drifter on Vita/Wii U. They are great publishers/developers and I could imagine them working on the game with little issue.
Maybe when the developers health situation gets better and he feels well enough to continue work on the game if he chooses to do so, he likely will talk to the bigger porting houses on the Vita and see what happens.