For the client? Thats already solved using either network draw distance/bubble or network draw distance update rate using a bubble. I forget the term but basically only players that are up close will get a fast update rate, the further out it goes, the slower the update rate. This already exists in quite a few games, even Battlefield. For the server?, I'm not sure of any real world examples, I'm sure its difficult. Latency and network speed between local servers means its manageable if coded done correctly. It really depends on how talented the developers are I guess.