I still think Apple is planning to eventually introduce some form of touch screen support to OS X, and I would not be surprised if it was some sort of hybrid iOS/OS X.
They hinted at it (sort of) a few years ago when they did the whole "Back to the Mac" thing. Remember they introduced a bunch of features from iOS into OS X? One of them was Launchpad. I always wondered what the purpose of Launchpad was. A little useless seeing a giant grid of icons on a 24" monitor, no? But on a touch screen...
The last couple of OS X previews they kept talking up these beautiful, amazing, full-screen modes they were adding to a variety of apps such as iPhoto. How great is it to work in full-screen! This, after so many years of "we don't do full-screen apps on Macs, that's why the green button is to OPTIMIZE the window size, not MAXIMIZE the window...."
And of course we're all used to multitouch gestures on our big, awesome trackpads, the likes of which no Windows ultraportable maker has yet been able to duplicate.
I suspect Apple is watching Microsoft and learning from their mistakes. WinRT was a flop, I agree. But you know under the hood, WinRT is really exactly the same as regular Windows 8, with two key differences: (1) it's compiled for ARM instead of Intel, of course, and (2) it ships with a setting that ONLY allows it to run code signed by Microsoft (e.g. obtained from Microsoft App Store). There is a jailbreak available for RT that turns off this code-signing setting, allowing it to run any Windows software compiled for ARM. Office for RT is basically regular Windows Office just recompiled for ARM. So the only technical reason why WinRT couldn't be just like normal Windows, is the hassle it would be to get developers to recompile all those old legacy Windows applications for ARM. Of course, that would be a huge headache, and I'm not surprised at Microsoft's choice to keep it closed.
But Apple is in a much better position, if they wanted to, to get developers to build software for both ARM and Intel. They've done it before -- twice -- during the 68K to PPC and then the PPC to Intel transitions. Fat binaries, Universal binaries, Rosetta... Apple users and developers are no stranger to this.
Also, look at the Geekbench scores for the latest ARM chips... the iPad Air scored almost 3 times higher than the computer I'm using to type this post (2007 Santa Rosa MacBook Pro). If not already, then very soon, these mobile chips will be plenty powerful for everyday computing tasks.
So, if Apple wanted to, I think they could introduce some kind of hybrid product. Maybe this rumoured "iPad Pro" will run full OS X applications, either with an on-board low power Core processor, or OS X recompiled for ARM.