I just thought about it, but for PvE people can be on any realm outside of maybe Mythic difficulty. Blizzard recently added the ability to do Heroic SoO cross-realm, and that technology is going to still be in place moving forward. So, people can stick to certain realms for PvE and still play together, and then join Magtheridon (or wherever) for PvP; and even with the ability to use CRZ we can still put together large-scale battles, but enough people need to be from the parent realm.

Quote Originally Posted by JackBurton View Post
In unbalanced Realms the Battleground Que times are way shorter for the team that is the underdog numbers wise.
BG queues haven't been based on specific realms since somewhere around BC/Wrath when they were based upon the Battlegroup that the realm was in, and when the pre-Cataclysm patch hit every server in the same region (NA, EU, Asia, etc) was thrown into the same queue with everyone else -- Even Arena queues are no longer Battlegroup-specific and they're now region-wide, as well.