You didn't think they can make it thinner than iPhone 4/4S, did you? And sure enough they did. So, of course they can make it even thinner than iPhone 5 for future iPhones. Just a matter of will they do it.
I'm sure they can make a wider iPhone 5, but they decided not to because we all have stubby thumbs.
I'm sure they can make a wider iPhone 5, but they decided not to because we all have stubby thumbs.