Lets be realistic here:
Something like "quick reply" or "iWatch connectivity" or "iTV support" or "Siri improvements" or something to that effect would
in no realistic way be something that would be exclusive to the next gen phone on iOS 7. If these were features, they would be added to the iPhone 5 as well. iWatch/iTV and Siri stuff being exclusive to the next gen iPhone would make no sense, considering there are already two other phones that support Siri and why would you lock your product connectivity if they're all running the same OS and all being sold at the same time??
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So, something realistic to be exclusive to iOS 7 on iPhone 5S? Probably nothing. Nothing HAS to be exclusive at all. Probably some camera features to take control of the rumored updated camera sensor and dual flash. I'd expect a Night Mode or maybe this no "Mogul" setting.
There's also the possibility that if this "fingerprint scanner" technology is added (which I doubt it will be), it could be tied in with phone security. I can see it being used with Passbook or NFC payments if they add NFC.
It's possible that the iPhone 5S will exclusively support AirDrop with macs that support 802.11ac wireless.
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NFC is the Blu Ray of mobile tech - "why?!"
Blu-Ray kicked off very well actually. Almost all disc media is being replaced with Blu-Ray. The PS3, PS4, and Xbox One all use Blu-Ray as their main disc media. In fact, Apple is the only hardware company that doesn't offer Blu-Ray optical drives instead of a standard DVD one.
NFC on the other hand, just isn't as useful as planned. Things like WiFi Direct are more useful for sharing files, as evidenced with AirDrop and Galaxy Group whatever, because it allows you to share more than one thing without bumping phones. NFC Mobile payments are poorly adopted, meanwhile many retailers are in full support for features like Passbook and mobile coupons instead.
I think that saying "NFC is the Blu Ray of mobile tech" is unfair, because at this point in Blu-Ray's life it was already achieving widespread usage. NFC is probably not going to take off, at least not for very long.