If you’re itching to play as a wealthy trading-state of Greek colonists in Total War: Rome 2, good news, Massilia will be added as a free faction on 20 November. That news was apparently announced on a Total War: Rome 2 livestream, but repeated through their usual forum channels as well.
The free DLC (or free-LC if you must) will be accompanied by a standard paid DLC called the Black Sea Colonies Culture Pack. This doesn’t seem to have been given a price yet, but since prior Culture Packs have been $8.00 USD each that would seem to be a reasonable estimate.
The specific Black Sea Colonies that will be added are Cimmeria, Colchis and Pergamom. They all “claim Greek heritage,” but the distance from their homelands has resulted in subtle cultural changes. Each of these factions will have a unique set of traits and a “hybrid unit roster” that reflects their diverse culture. You can read more about each of them on the Total War factions list (scroll down until close to the bottom.)
Massilia has a faction entry too, which you can read here. According to the announcement, Massilia has “has come to embrace Gaulish culture, military units and battle tactics,” so expect a few Gaul-inspired troops in that line-up.
It’s possible that Creative Assembly will combine a few changes and bug fixes with the automatic Massilia update everybody will receive on 20 November, but no forthcoming general patch has been confirmed at this point.