DLC 3 and DLC 6 are shipping with a new map (not map script) so it could be a hint to what civs they include. Middle-east and N.America are very possible maps.
The only new maps I could see them adding would be Middle East and Americas maps. If that's the case, I'd guess that the packs would either go:
Maya & Colombia; Ethiopia; Babylon & Byzantium (Middle East Map); Portugal; Vietnam & Kublai Khan; Iroquois (Americas Map)
or (preferably for me)
Maya & Colombia; Ethiopia; Iroquois & new Native Civ ?Navajo? (Americas Map); Vietnam; Portugal & Byzantine alt leader for Rome; Babylon (Middle East Map)
This way they could release groups based on region and introduce new maps with the new regions.
Obviously I make a lot of assumptions here
thoughts?