So let's go with a touch screen replacing the whole keyboard/trackpad surface, but with vertically controlled extruding/pressable pixels and haptics, so we get a physical keyboard of whatever dimensions and arrangement we like, and any other types of controllers.

I wouldn't mind a "physical" touch scroll bar on the right side of my keyboard, controlling vertical scrolling on the screen with more accuracy, less swiping.

If the tops of the pixels can roll, it could actually have a physical "thumb" button that you slide up and down. I.e. pixels going up and down to "move" the thumb. The rolling making it feel smooth and frictionless when you "move" it.

Games and other tools could create some. awesome interfaces. Swipe down to get your keyboard sliding back.