This information comes from Team Ninja head Yosuke Hayashi…
“One thing we felt when making Dimensions is that players view and treat console and portable games completely differently. This is something that needs to be reflected in the game design as well. In fact, we are discussing daily about the way to make a 3D action game such as Ninja Gaiden into something that would be appropriate for a portable game system. When we get this answer just right, we will show it to all of you so stay tuned.”
It sounds like Ninja Gaiden 3DS isn’t very far along in development. However, if the game turns out to be anything like Dragon Sword, I’ll be pleased!