Some applications are going to feel stuck in one interface or the other, but it is already the case that some applications already are mostly mouse and others are mostly keyboard: the touch screen is just another interface that is available, and for many applications it is in fact totally doable to make the transition between the touch screen and the keyboard as seamless as moving your hands from the keyboard to the mouse: it would be awkward to expect to see two views of the app, one mouse-driven and the other keyboard-driven, being flipped between via an MVC paradigm.
it would be awkward to expect to see two views of the app, one mouse-driven and the other keyboard-driven, being flipped between via an MVC paradigm.
I'd expect that both views would be fairly similar, like the two different views on an iPad vs. iPhone app, or when rotating 90 degrees. The OSX view would be tailored just for it; larger screen size, multiple displays, different input, etc... Apple is already unifying the look-and-feel of OSX and iOS apps, getting ready for some sort of merge (iCal/Calendar, Pages, Reminders in 10.8).
We're probably going to see five major input devices in all computers a few years from now. Keyboard, mouse/touchpad, touchscreen, voice, and physical gesture (e.g. Kinect, eye tracking). No piece of software has to use all of them, just as many as necessary. So I wouldn't expect "every" app to have an OSX and iOS mode.
In the future, a sixth input device will probably read our thoughts directly. :)
