Honestly, if the devs refuse to outright eliminate the melee's entire 60%, I think NIN and (I guess MNK's, though I'd argue DRG too) DR should at least be brought down to 45% and DNC, SGE and RDM should be brought up to 45% to create a 3rd category.
I find that unlikely though, as it's probably easier (and lazier) to just divide the DR levels by roles.