i think it still will be 16.32.64GB, no need for bigger capacity for personal use.
Statements like this remind me of the following "tale".
At a computer trade show in 1981, Bill Gates supposedly uttered this statement, in defense of the just-introduced IBM PC's 640KB usable RAM limit, "640K ought to be enough for anybody."
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Whilst I don't expect a storage capacity bump with the 5S, it's very shortsighted to say 64GB is all anyone needs.
I use my iPhone as a convergence device for phone & messaging, photos, videos, internet & music.
I've barely scratched the surface on recording home videos and storing Hollywood movies to watch on the road, but I'm still near the 64GB limit.
The iPhone is more powerful than your main computer was 5-10 years ago. If I truly wanted to fully embrace all of its capabilities, I could easily store 500GB or more and that's just by today's standards. Who knows what the next few years will bring?
Personally, for speed of processing for example, I'd like to be able to perform services like voice dictation and real time language translation locally on the device, without having to access the cloud. Features like this would demand storage.
4K or 3D video recording, the list could go on & on.