I used Windows 8 on a touch screen "tablet" style computer for about three weeks. I mostly kept it docked with the bluetooth keyboard in front, though occasionally picked it up.
My impressions using the metro interface:
* it works a lot better than I thought
* reaching out and touching the screen begins to feel natural. It is not fatiguing compared to using a track pad.
* I was switching back and forth between a desktop running W8 and had to catch myself from trying to drag things around with my finger.
My impressions using the classic interface with touch:
* horrible! terrible! I had no mouse for the touch-enabled computer and that drove me nuts when not using the metro interface.
To my mind touch will work great on a laptop, but the OS and apps have to be optimized for touch.
I think before Apple would consider a touch interface on regular OS X, they'd have to revamp the UI of the OS to accomodate. It's a lot more than using iOS-like scroll bars.
And if they keep going strong with the iPad, I just don't see why they would do this. iOS IS the touch-optimized OS. Over time the hardware will get more and more powerful, and there will be less and less reason for Apple to make non-iOS devices.