The lack of a rear cog is its crowning achievement :) Surely the only thing better than single speed is no speed?
Must have a 5T rear! 9T is possible but less than that you can't fit hub far as I know.
The chain guard may be like the HEBE Chainglider fitted to some bikes. That's ok but does need cleaned - as do chain tubes on recumbents. One of my customers had a Chainglider as standard on his VSF bike. The guard lasted 3 years. His chain was a wider 8 speed on a Rohloff so was still ok after a clean I think.
Arellcat has run a Scotoiler on one of her bikes to extend chain life.
If you want to look at something advanced and in production then the Flevo Greenmachine has been there and done that. The chain is inside the frame and the Rohloff gear is in mid of bike. How dos it ride? OK enough but pedals seem high. I tried one round outdoor track at Sloten Amsterdam. Frame does make some transmission noise. Might not be to everyone's taste but is quite a new take on what to do with transmission.
The Seoul cycle design competition 2010 does not address any of the things that actually keep The Bicycle Works in business.
This of course is a good thing!