You know, I was actually wondering about this when I saw a video on the 1DX and the guy was popping photos like an uzi. I thought, "now this can't be good for shutter life." I blew through a quarter million shutter actuations on my 1D4 relatively quickly and I'm now to the point where I use my 7D for less important jobs because it's almost a disposable camera to me.
I really hope there will be some way to dial down the FPS because 99% of the time I wouldn't want to be popping that many. I'd like to be able to have more options than either 4 or 12. It would be great to be able to tell the machine exactly how many FPS you want, program that like into a C1-C3 button, turn and let 'er rip.
The point of 12 FPS is "there's no way I can miss this!" If you have to fumble through layers of menus to turn it on, it sort of misses the point. If you leave it on all the time, you're filling your hard drive with needless photos and putting unwanted wear and tear on your machine.