I agree that they need to improve app-switching/multitasking. Being able to swipe between running apps is a good idea, and would probably help avoid an early death of the home button by having to double click all the time. But if swiping is the answer here, wouldn't it be better to just use the whole screen to swipe instead of a little button? As someone else said, maybe I am just being short-sighted. Afterall, I am nowhere as visionary as Apple's design team. But it seems using the whole screen since it is already capacitive would be better.
It would have to be a multi-finger swipe, which would only work if you were using two hands to operate the phone. The vast majority of the time I use my phone, I am only using one hand. If the home button is touch sensitive, a swipe could be done there using just the thumb.