So this is basically a new villager that owns the npc village around him. If you annoy him he will now let you enter the village and if you somehow can (like sneak in), iron golems will attack.
If you defeat the village master he will drop an crown, with this crown you can build 1 village from the "available-to-build" list, the 1 villages available is "Kingdom" and it will create itself.It will take about 3 minecraft days to create the town hall(image 1),the church(usual npc village church and 3 small homes.You can use 50 rubies to upgrade the town(this will add 3 buildings per upgrade). Each upgrade will cost 50 more rubies then the last upgrade.There will be some new villagers like warrior (attacks enemies), nurse (heals you) and even Women looking npc villager( like an ordinary villager but looks more like a girl).

I think this is a good idea because having a team with you on your single player world will be great because you can make tactics to attack mobs ,or even just strolling in you lovely town! This would give players that have defeated the Wither and the Ender dragon a new quest to complete, plus having more hilarious Squidward People-things would be awesome:D!!!