I came across several posts which suggest that action shooters might use Kinect. Personally, I think it would be a great idea, though I can't imagine how difficult it will be trying to keep your cross-hair exactly where you want to!
I think the Kinect should receive an update, before developers target it as a serious platform. Playing stuff like Boxing and Fruit Ninja is OK with the current hardware, but I don't think it would be able to do justice to more serious games.
Thinking back on it I really do not know anyone that used a Kinect for FPS. Is that what you are talking about or just general shooters? Most people I know are using the Xbox for anything like BF or COD.
I think the Kinect has great potential for use with first person shooters, but right now, the technology isn't where it needs to be. Like James said, some games are okay played through the Kinect, but I don't think it's sensitive enough yet for use with games like Call of Duty.
Getting into the serious game role could do wonders, I know many people that only want to play shooter style games. These people will not try anything else new, they want what they want. If the demand is that high they need to do something about it otherwise they are losing new customers, ones that could be with them for years to come.