In the next server update they plan to implement a PvP reward to help reduce the drastic increase in barbarian nobling. When a village is nobled, the nobling player will recieve whichever flag was stationed inside the village at the time of it being nobled. They hope this will bring new excitement in to the game, and remind players that in this game, the goal is to eliminate yours and your tribes enemies.
Currently there is a 24 hour cooldown for changing your flags. This will not change. However, should your loyalty be dropped, you will not be able to remove your flag until it reaches 100% once again.