Just think outside the box, cause you know Apple will. As I said already the API for OTA updates for Apps is also available, meaning any App could patch itself and any privileged App could in theory patch iOS.
Though I do not discount the ability of a hacker to break a static OS, the constant battle with a changing iOS in an iCloud world is going to be a much greater challenge than even the last exploit - which took quite a long time and some real luck.
It will be interesting to see how serious Apple is about closing any security loophole. They certainly have the money and resources to be very, very serious about it - and with the framework in place for iTunes, iCloud and OTA incremental updates, you may indeed be able to jailbreak, however it may come at the expense of never being able to use iTunes, iCloud or receive any App or iOS updates. That may indeed be the new price of admission.
Again, we can all only speculate at this time. I'm simply looking at the tools available should they get serious about the problem, coupled with the rumors of Jobs' current obsession with security and making my personal prediction. YMMV
-t