I'm not sure about the flip part but I would like to see the MBA morph into a laptop/tablet hybrid, bit like the HP machines I've seen. So you can dock the screen and use it as a laptop or take the screen off and use it as a touch screen tablet. I can really see the benefits of that. Presumably that would mean it would have to run iOS rather than OSX but it sounds good to me. I don't think they will do it this year but maybe next year.
I can easily see the MBP, MBA and iPad merge into one product someday. We can call it iMacBookAirPro.