I'm not sure I'd want to negate the weight benefits of singlespeed by adding disc brakes... Plus, the whole aesthetic of a singlespeed bike is steeped in simplicity. Disc brakes are less simple than cantis or V-brakes for lots of reasons.
I certainly don't plan on making the switch myself.
I enjoy waving my middle finger at "traditionalists," so hell yeah, disc brakes, flat bar, singlespeed!
It would be amusing to build a "high tech" single speed bike.