It is possible to do a 128 player server as the mod yoshiro linked showed, and apparently after reading those comments apparently the next update is 1024 player servers, 1024 player battles in RO anyone?

(Off-topic: even though 1024 player servers would be amazing and epic it just wouldn't work in RO)
It should be possible to make an 128 player server then in RO, the only problem be would is if the server can handle it, well if the server is powerful enough the person is running then I don't really think it would be a problem even if the maps were designed for 64 players. I played 64 players in cod4 and those maps were not meant for that lol and it was still amazing to play.
So we just basically have to wait and see if someone who is going to be running a very powerful server is going to try and get a 128 player server running and then test it to see if it is stable. :IS2: