If it was by another company, you might say it's doomed, but not by Nintendo. They've already invested a lot of money in this, and they've got a lot more money to continue advertising and make their own games. What they can't afford is to have no console available for sale for the next 6 years (give or take).
I disagree with your belief that motion control is a gimmick. It's awesome. I can actually point at an enemy and shoot him (pulling a trigger if I use an attachment) instead of turning with two sticks, I can move my arm to move the players arm and swing a sword, I can tilt a wheel to control the direction of a car, and so on. It adds a whole new level of realistic gameplay.
Also, having a second screen on the Wii U is awesome, especially the offscreen gameplay. I look forward to using it as a scope too.