Try adding a few zeros on that estimate. About 10G upward to 100G for a server beffy enough to run the game. Even then each server is limited to a few players when you have a dedicated connection to it. Not to mention the networking equipment needs to service 10,000 or more servers in a farm. Plus the fact they support 4 different platforms, as they can't run on the same server together. If they went exclusive to xbox then they could have used their farm that maintains close to 300,000 servers.