I think one of the incoming will be a Magitek Knigth tank job with a Gunblade, with Garlean theme. Something like the Legatus. Could be also a Gunhammer (like Nero) or Gunspear (like Nael).

Dancer probably will have Thavnairian theme. Could be melee DPS or healer perfectly, as there are already a lot of glamour that resembles like eastern dancers.

Blue Mage is very complex to implement in the traditional way. But could be also a mid-eastern theme with the use of Scimitar. Maybe Persian themed. Mainly i'd say DPS.

Geomancer has been already hinted in Astrologian job quest and Swallow Compass. It is obviously eastern themed too, origins in Hingashi. But they resemblance to a Conjurer makes difficult to differ from it.

Gunslinguer with two guns can be from Garleand, but now Ishgard has the machinist technology, could be tied to this ones too.