Marco Arment has a much more positive spin on the opportunity provided by Apple's root-and-branch redesign:

Apple has set fire to iOS. Everything’s in flux. Those with the least to lose have the most to gain, because this fall, hundreds of millions of people will start demanding apps for a platform with thousands of old, stale players and not many new, nimble alternatives. If you want to enter a category that’s crowded on iOS 6, and you’re one of the few that exclusively targets iOS 7, your app can look better, work better, and be faster and cheaper to develop than most competing apps.

I'm with Marco. The iOS project I'm working on is going to be reconsidered in light of iOS 7, and not a moment too soon. When the iPad version lands I'm installing the beta on a development device.