A Wii U release for Metal Gear Rising Revengeance is still a possibility, if Konami sees the demand for it. This was said by Platinum Games staff member JP Kellams when he was asked on his Twitter what the chances are for a release of the game on Nintendo’s newest console.
Kellams explained that Konami could request Platinum Games to develop a port if they see the demand for it, and he adds that not the studio itself, but the publisher (in this case Konami) ultimately decides what consoles the game will appear for.
It seems that a Wii U release for the game is not out of the question after all.
Source: JP Kellams Twitter