And we'll be expected to stretch our arms up to touch ever-larger-growing screens all day long?
At the moment I'm sitting in front of a pair of 27" monitors. Trying to use a touchscreen that big for extended periods of time is just going to be fatiguing.
I'm not saying it's going to replace mouse and keyboard but a screen that doesn't support touch at all will soon feel archaic. Even now I often find myself absent-mindedly trying to close windows with my finger on my dual-screen setup.
Remember that the ergonomics of a traditional workstation are driven by decades of mouse and keyboard input. As touch becomes more popular the layout will change to support that.
At the moment I'm sitting in front of a pair of 27" monitors. Trying to use a touchscreen that big for extended periods of time is just going to be fatiguing.