There Is No Dancer (yet)

[Kurogaea]

It's not even speculative. The lady in the trailer used monk moves.

[Sub-job Combinations
Monk
Monk is the best choice as an early sub. It provides added hit points, one tier of Martial Arts, and helps put a bit more damage behind your hand to hand attacks]

Thats a part of a Dancer Class Guide on FF11, saying Monk was the best subjob choice for Dancer. Also we have 3 melee dps atm against 4 ranged dps. No one knows for sure what Red Mage will be, a tank or dps or even a healer, but if it isn't a dps, that spot would be open, maybe for Samurai, but then what would healer be? Perhaps close range healer. Sounds silly yeah, but then you have skills for monk like Mantra, so that possibility is still there.