OS X is going down the same path as iOS, too: Mountain Lion scolds users for downloading apps without going through the App Store; this can be disabled by digging around in the system settings, but I can envision a day where you'll need to open a terminal to set a system property from the command line, and then a day when they simply disable unsigned binaries from running altogether.
What is Apple going to use for their own work? Their developers and designers are power users.
It's certainly possible that the Macbook Air would switch to ARM in the next few years, but until you can write software for an iPad on an iPad, there's no getting away from OS X and serious processors.
