firstly as previously stated people are getting bigger and i hate to say it, fatter. can you imagine what a 34mm watch would look like on a 6' 4'' 25st guy with rolls of fat? it would look ridiculous regardless of quality. i also think that the uber watches will slowly disappear like the 55mm repro's of the WW2 observors watches. they were made to wear over jackets and look odd on the wrist.
on the whole i would hazard a guess that the Panerai/B & R size pieces are here to stay. firstly while people want them they will still be made and because they are available people will buy them etc etc, a not so vicious circle.
i like all sizes of watches with 34 mm being about the smallest and 48mm being about the biggest and i think they are here to stay. its great that people are able to wear what they like without the constraints of size. it makes the world a much more interesting place.
Graham