I am not surprised Japanese companies trade patents. Why do Canon and Nikon share so many common features (IS vs VR) yet we never see lawsuits flying around? I think they are far more collaborative than we believe. They'll rather help each other out than allow a competitor from another part of the world to sneak up on them. See what happened to the Japanese TV industry?
I do not believe we'll ever see a Nikon camera with EF mount. But we may see improved Nikon TSE lenses, 70-200 f/4 lens, MPE lens. On the other hand, Canon may release a 14-24 lens, sensors with improved DR (like the D3s) etc.