It will go like this:
- Apple releases 6.1.3 that kills the l337 h4x0r 3v4z10n jailbreak
- Jailbreakers whine briefly, then strenuously avoid the update
- Apple will cherry pick good jailbreak app concepts (if there are any left)
- Apple will release iOS 7.0 with those concepts
- People who JB-ed for those concepts won't need to jailbreak any more
- People who JB-ed to steal apps, videos, music, etc. will keep on doing it
Meanwhile, some other group of l337 h4x0rz will exploit some other jailbreak technique that Apple can, yet again, quickly slam shut. Rinse, repeat. And some day there just won't be another jailbreak technique. And we'll be done.