If you think about it guys osi's software is extremely old. 5-6 years old to date. They use a HUGE amount of soloris machines for each shard (like 7-8), and each shard can only support 2-5k people.
If you were around when OSI allowed housing in trammel, you would remember that each shard being logged in with max of 5k people COULD NOT HANDLE IT.
Technology is advanced, and I am willing to bet that an extremely solid\well built server made today could handle almost double, or tripple what OSI can handle, and only on one machine. (As long as the machine can handle it).
The feature of server farming and multiple servers isn't really needed.