I have to be honest that I think some are looking at this subject and limiting their responses to portions of the broader topic of whether or not tablet technology will advance to the point where it will be possible the things we currently believe a desktop based DAW is required for.
People keep referring to the input output limitations, as the tablet as a replacement for the studio be it professional, project, or home (I'm unsure how that even fits into the equation as I can't see why one would want to), and the limitations of a touch interface for serious mixing. I don't really see those as the factors at play.
In the scenario I see, a tablet could become the center point of a recording system just as the desktop has. The desktop has limited input and output by itself so we use external interfaces, a PC is only a small component of a studio, whatever that level of studio one is using. One still requires mics, monitors, keyboards, a mouse, control surfaces (if one chooses to use them). As the iPAD dock shown earlier, the input/output/monitor control issue can be solved with keeping the console and just using the iPAD as the capturing component. Think of a mixing desk where a engineer simply comes in, drops their tablet into a dock, launches their DAW and has all the input/output/channel, buss capabilities afforded them from a traditional studio setup, the tablet has simply replaced the DAW portion. The dock could even have a keyboard and mouse attached, or the tablet could use Bluetooth to perform this connectivity.
Once captured, the engineer could then choose to mix on the console or take the tablet home to work with in say a smaller control surface interface/docking system that has less input/output capabilities such as the Alesis unit shown ealier but with similar controls like say the V-Studio 100 with it's control surface capabilities, motorized fader, ... Or, they could use the touch interface for mobile mixing if that's what they wanted to do and be completely mobile at times when it was necessary.
In the past 3 decades we have gone from this:
To this:
From this:
To this:
From something similar to this (note this is actually from 1985):
To this:
From this:
To this:
The images show how things have gotten smaller, yet exponentially more powerful over a relatively short window of time, and that our way of accomplishing similar results has also changed - we adapt to the technology of our times. In my scenario the tablet would simply replace the desktop DAW portion, not the other components required.
My thoughts on this subject are less about the "it will happen", and more about the "it could happen" given what I've seen change in my life. I guess I'm showing my age a little bit but I've been a adult through all this change so far.
Maybe I'm a bit of a dreamer, but I'm certainly not a denier that change happens whether we think it will or not.
Something to ponder.