I wouldn't think it would go too well in terms of how they code the aircraft but it's an interesting idea.

Yes, it's posible. My friend use touchscreen with most of aircrafts. I didn't saw this in action, and he is on the trip right now, but i can ask him more about when he returns

I'm currently using an Acer T232HL touchscreen for FSX.  My eventual plan was to use a touchscreen as a panel monitor.  It was on sale however, so I bought it on an impulse.

 

I redesigned my simpit and mounted the touchscreen on a moveable arm, so I can place it wherever I wanted - the plan was to use it alongside one of my other 24's for now, and with perhaps a 40" in the future.  However, I ended up being so impressed by it, that currently I just have it as my main monitor.  With the arm, I can extend it towards me so that it's up nice and close to me.

 

Some planes of course work better than others.  I can completely control something like the dodosim 206 for example.  I love the start-up in that machine, never need to touch the mouse at all.  Most of my Carenado fleet works well too.  Little things like touching a visor to flip it up is really, really cool.  However, more complex planes like the Milviz F-86 are useless for the touchscreen, as almost all the switches use both left and right clicks.

 

I haven't used it yet with anything with an FMS, but I'm guessing it'll work nice for that.

 

One thing I've discovered, and this is particular to how and where I have the monitor placed, nothing to do with the touchscreen (except for that I've discovered this because of the touchscreen) - there seems to be a perfect sweet spot, really noticeable with military jets, in terms of eye placement to monitor.  When I have it placed just right,  and I throw the plane into a maneuver that causes the FSX head movement to bring the plane closer to me, you really get an immersive 'wow' moment.  I think it has something to do with the monitor floating in front of me, as there is no longer a desk in the bottom of your vision.