In an interview with Kotaku earlier today Team Ninja's Tomonobu Itagaki said that he doesn't plan on making any more Ninja Gaiden games for any platforms following the release of Ninja Gaiden II for the Xbox 360.
"Personally I think we were able to create the definitive 3D game in this series so I'm not planing on making any other games in the series," Itagaki said through a translator. "So I hope fans treat this as a swan song for the franchise.
"I think we were able to achieve everything we wanted with this game so anything else would be extraneous."
When asked if he plans on making a "swan song" Ninja Gaiden title for the PlayStation 3, Itagaki replied " that would be ridiculous."