While I ascribe to the theory of multiple universes, and there may indeed be several in which Apple is a clown made entirely of candy, in precisely none of them was iOS 7 not going to debut on time. If you need any more evidence of that, I give your Mr. John Paczkowski of AllThingsD:
“Yes, yes — it’s essentially a repeat of the iPhone/Leopard scenario,” one source said, referring to Apple’s 2007 decision to pull engineers from OS X 10.5 to work on iPhone. “Not as much of a fire drill, though. It will ship on time.”
And Mr. Jim Dalrymple of The Loop:
Until Apple announces something, it can't be "delayed". If they're not meeting internal schedules, if they're adding resources from other projects, if they're pushing features out to future versions, if they're doing any number of things a company their size does when working on a project of iOS' size, that's not "delayed", that's "development".
It's happened before, it'll happen again. Year after year after year, it's mind blowing how this keeps being a story. The day Apple isn't racing flat-out for the finish line is the day I'll start to worry.