Since we're simulating technological progress to some extent (from hunter-gatherers to agricultural, hide to silk and steel, tribal to feudal etc), and since the worlds are supposed to last forever, the game should support really long-term community projects.
My suggestion is that we have the option to unlock "technologies" as the world goes on, which in haven terms would be translated as new recipes, mechanisms, structures or available skills. I think it would be best if this depended on mutual cooperation, for example:
. By implementing a pool of global experience: players could sacrifice their XP, in chunks of 10k, to contribute to the global pool. When a certain number is reached (say, 1 million), the respective recipes would be made available to every player from then on, without restriction. Maybe there could be a scoreboard naming the kingdoms whose players contributed most to the pool too.
Reason: to give us something to look forward to once the worlds start becoming more permanent. Related: viewtopic.php?f=48&t=50986&p=674585