It WILL be a twin turbo beast! Not NA, not supercharged, turbo!
Interesting bits of info, the RS5 test vehicle has been running around WITH an NA motor, that has a dual throttle body setup. This has been part of testing for the chassis tuning and pilminary transmission (dsg) testing.
I think that the test vehicle is what is throwing the impression of it being NA, as it is, but the final product will be TT!