Pillager Towns/Cities

We all know in end game there isn't much to do other than build, farm etc. but what if there were pillager cities, things that could only be entered after end game. There could be pillagers walking around and if you stay for too long maybe a "reverse raid" could be initiated where there could just be a harder version of a raid, after this maybe you could receive a reward and a boss could be summoned if you collect 5 pieces of these victory items, the boss could be a giant ravager for example.