This sounds cool. The cyclical nature of the game reminds me of A Tale in the Desert. I tried playing that once but quit after ~30min because I couldn't find anyone else/the game sucked. But I digress. Your idea:
The migration from one instance to another would also have other problems if done en masse: overpopulation and therein inability to support the new arrivals on the now even quicker-depleting resources. Could this create an effect where there's a sort of cycle of people essentially going around leeching the rich places until they're unstable, moving to the next, and repeating? By the time they get back to the first instance, it will have already reset and regained its prosperity...maybe.
Curious idea though.
Hopefully the price of travelling between worlds would be high enough that people couldn't just jump between them constantly. But certainly I would like to see scenarios where people fleeing from one world are not welcome in another one because they overpopulate it. They would be hated like illegal immigrants are in America.
On the other side of the coin, if you landed on a world with a relatively low number of players, it would be fun times all around... until everyone else hears about this world and it ends up overpopulated again
The most obvious money sink would be food, but if it wasn't handled properly it could get really annoying. Then again people playing this game are already resigned to the possibility of permadeath if they don't keep on their toes so I guess having to buy food constantly really wouldn't bother them that much.
Also, at the very end of a world, there is an uber-powerful Antichrist sort of boss. If the remaining players can coordinate to defeat him, they get to carry their characters over to the new world with a hefty reward, perhaps even becoming the kings of the new empires. But being killed by the Antichrist results in permadeath, so few players would dare to face it. Thus, powerlevelling isn't enough to reach the top of this game - you also need to be brave enough to risk all your hours of powerlevelling on a shot at the endboss.
The top players in WoW are fat nerds with nothing else to do with their time. The top players in Dying Earth are fucking badasses.