hmmm....
BLM rooted caster
SMN semi-mobile caster
RDM semi-mobile caster
MCH highly-mobile ranged dps
BRD highly-mobile ranged dps
DNC ??? ranged dps
Assuming they are trying to retain some of the job identity with dances as buffs for the party... my guess is that DNC will be a rooted ranged dps. Perhaps it's buffs will be stronger than bard at the cost of movement during dance phases. I mean in my mind... you can't really run around while performing a specific dance... that changes the steps so the dance proper isn't really being performed anymore.
Of course not being able to do anything but dance during dances would also be weird and not really in the spirit of the DPS role... the only ability I can think of that requires complete PC inaction to maintain is AST Collective Unconscious (oh I guess BLU Diamondback too edit: oh and that thing that SAM has to build gauge...). So I'm thinking their GCD attacks (whether that's a 123 or individual attacks) will still work while dancing, but they won't be allowed to move without cancelling the current dance. While not dancing they'll be highly mobile, but then the game will be figuring out when and where to be positioned to safely use dances.