A third party developer will be handling the upcoming port.
http://www.nintendoworldreport.com/news/37023/two-brothers-still-slated-for-wii-u-release
Two Brothers is still slated for a Wii U release.
The game, a retro style RPG funded by a Kickstarter campaign, was due for release in January of last year. However, numerous delays have plagued the game and despite a release on the PC, it has not been released on the Wii U.
When asked if the Wii U version of the game was forgotten about, developer Ackkstudios responded on Twitter, "not at all!! It's being ported by another developer who is really good at wii u ports. Ensuring it gets the love it deserves."
It is unknown which developer is working on the Wii U version of Two Brothers and there is no current release date.