Problem: A lot of people get upset about new worlds and feel like their progression is lost from generating new worlds and that their countless hours and labor is pointless.
Idea: The idea I had was a vanity/prestige reward system. The idea is to take the player's stats and turn them in a score number at the end of each world. The score determines the tier of a vanity items, emotes, or prestige of some sort that affects the players in the new world in no way what to so ever other than allowing the player to show off what they have accomplished in previous worlds.
As an example, lets say I obtained a score of 100k which I guess would be pretty low. So I get a little emote that I can do to show other players I obtained a score off 100k-250k tier. Better the tier, the better emotes and you also would get access to previous emotes.
This helps give a little reward for competing each world and puts a little bit more aim in obtaining a better score.