I think the larger realm populations are going to have some noticeable differences in the player experience over Vanilla. There are a couple of things that come to mind when reading Blizzard’s mentions the increase capacities of Classic vs Vanilla.
- End game farming: Will this not cause major issues with over crowding? This was already an issue in Vanilla.
- Economy: How will this affect supply and demand? Economy was vastly different depending on realm population back in Vanilla.
- Global Chat Channels: More population can lead to more spam? Vanilla already had a lot of people re-posting in channel just because of how quickly a message could get pushed out the chat window because to the shear volume of people using them.