Take a look on how the official White-Tiger server does it. First, it has some balancing changes, second it starts with a pre-established community and government concept that serves as a framework for people to play in, third our computer lab recipe requires several ten-thousands of goods from all professions in the game, fourth we usually have a world wonder monument built every cycle that requires lots of resources of all kinds. Alltogether despite the poor balancing we unfortunately still have in the game due to lack of fleshes out profession content aside from smiths and engineers, every player no matter which profession he plays has a use until the last days. It becomes grindy, though - but on the other hand you get a use for the endgame machinery that you usually would skip anyway, as you can shoot the meteor down the moment you get it on vanilla servers.
Obviously this doesn't work for every kind of players, but it's working well for us. Of course we also use an adapted worldgen with less water and more land for building projects and a higher difficulty than the highest default that we provide.
Oh yeh, and we focus a lot of players in the capital city, that is also built together. So pretty much three world wonders per cycle to create. That's enough to do for most people, of course not everyone is interested in that.
In the end it ever needs people that are willing to communicate, active admins that do organisational work or extremely engaged players that take that over and some kind of plan should be there. An evolving plan by the players while the game is running i've rarely seen, given a lot of people would need to step up and agree with each other at the same time - that works on whitelisted servers, but rarely on public ones.