While Keiji Inafune and Team Ninja wouldn't specify which platforms their new take on the Ninja Gaiden franchise would be coming to when they first revealed the game, it doesn't look like they were being cagey for the sake of keeping next-gen hardware a secret, as Yaiba will be coming to current generation hardware.
According to several job listings at Spark Unlimited for Ninja Gaiden Z, it appears that the game will be coming to both the PlayStation 3 and Xbox 360. The posts describe the game as being "a bold new take on 3rd Person slasher with Horror elements for the PS3 and Xbox 360." That's right, no mention of Nintendo's hardware, sadly.
Yaiba: Ninja Gaiden Z will be developed by Keiji Inafune, Team Ninja, and Spark Unlimited. Be sure to stay tuned to GameRevolution throughout 2013 for updates on the project.