We have 3 tanks.
We have 3 healers
We have 3 close range dps
We have 2 long range physical dps
We have 2 long range magical Dps

What we need is 1 more long range dps for both physical and magical. I think the next class will be another mage, because both BLM and SMN are sort of turrets standing there, immobile, and casting. But a mage with fast spell cast speed, potentially less damage, but more mobility(blink/flash) is what we need.

For ranged physical I would love a "druid", a ranger with a wolf or bear, like SMN has. Not a pseudo summoner as MCH with a turret that stands still.