iOS apps can only be produced on a Mac because that's how Apple wants it. In the unlikely event that Apple did decide to ditch the Mac, they'd port their iOS developer tools to another platform.
* Mac continues to evolve slowly, not have major innovations. Innovations that do occur will be on things that are aligned with iOS-like devices (like Launchpad, Mac App Store, Macbook Air's).
* Someday they will ditch Mac, when an iOS device can be used to (1) create new iOS apps, and (2) be a productivity machine (e.g. w/ keyboard / etc).
Those of us who like to poke under the hood will have to move back to Linux or something else.
