Nintendo doesn't own "the motion detection controller" generic patent or design, but only its specific implementations. Works on the tech were already started before Wii development began, and there was even one resembling a katana hilt. Nintendo itself uses a lot of 3rd party tech under license in WiiMote, Nunchuck and Balance Board, some of those tech were developed initially for robotics, avionics, aerospace, automotive and transport engineering and other high tech sectors, then components costs started dropping and Nintendo had not only the timeliness to launch its implementation for entertainment just when the price was right, but also the talent to design the first widely enjoyable implementation. This is a thing competitors can try to copy, but they'll arrive at most second, so, despite Nintendo can't stop them unless they commit blatant plagiarism, it has very little to fear, at least for the rest of this gen.
Stwike him, Centuwion. Stwike him vewy wuffly! (Pontius Pilate, "Life of Brian")
A fart without stink is like a sky without stars.
TGS, Third Grade Shooter: brand new genre invented by Kevin Butler exclusively for Natal WiiToo Kinect. PEW! PEW-PEW-PEW!

