I like the idea of merging bin and sbin dirs, since the distinction isn't really important in most cases. I would also like to get rid of /usr/bin/games, since its use is not much respected anyway and never made sense (who do games get to be a special class of binary but nothing else does? Throwing all pg* and mysql* tools into a separate dir makes at least as much sense).
I don't think getting into the business of putting binaries into different directories for categorization purposes is more useful than harmful. What is the goal? If it were to be done I think subdirectories of /usr/bin (or /bin if we're not using /usr any more) makes the most sense.