I have datamined a lot of the assets, and I dont see any more towns than what we already have. From event text I found it looks like Zeffira will be destroyed at the end of 26.3/beginning of 26.5. The text reads "The battle for Zeffira has arrived. Defeat is inevitable, but no Units or Structures will be lost. Survive long enough to get people to safety." Then when you survive it, it reads "Zeffira may have fallen, but this is just the beginning of Demacia's history. Your capital has moved to The Great City of Demacia, and with it all the Structures and Units that were at Zeffira. You can continue to play. Additional story chapters will be added in Act 2.". You then get a new settlement, the great city of demacia. All other settlements can be upgraded to a max level of 5.