Once Lion was announced, I thought that it was inevitable that OS X and iOS would merge into one OS that ran on either ARM or Intel hardware. I thought OS 10.8 / iOS 6 might be that OS. Clearly I was wrong, but it seems like Apple is still traveling that path.
I, for one, am looking forward to what I assume OS 11 will be. One OS that will work on your Desktop, Laptop, Tablet and Phone. The interfaces might be slightly different, the specs of each device will vary wildly (desktops/laptops will always be more powerful than tablets/phones) but the core functionality will carry through all devices.
I look forward to the day when any application (barring those that are limited by technical specifications) will run on any device. Instead of iOS apps and OS X apps, there will just be apps, and the devices you prefer to run them on.
OS X and iOS are built on the same framework, and they are slowly creeping closer to one another. I truly believe that this is what we're moving towards, and I can't wait.