It would be nice if we could improve RDM without simply stealing abilities from other jobs. Some new RDM-only spells would be good, and the devs already implied that there might be new spells coming via job points, what they are and how effective they might be is up for debate. Some improvements to the elemental magic system would indirectly help RDM, which has also been mentioned by the devs. Unfortunately we probably can't expect much more then that, it's always nice to dream though.