Above: set footage from the Prince of Persia sequel, Pup of Persia.
I am loving the new cross-realm dungeon grouping feature. Being able to run dungeons with friends on other servers is great, to the point where I will pay for this feature when it's no longer free. My question is: what do you think the odds are that they will extend this to raids if it catches on? That would be my dream, to be able to pull in a few RealID friends from other servers to raids. I realize there would be logistical problems (like they'd certainly have to disable the ability to get Realm First or other server-specific achievements for cross-server groups) but I think things like that would be a small price to pay to be able to raid with friends.
I think the service as it exists currently is a test for a broader, more robust system. I wouldn't be surprised if you could eventually do more with it eventually, like rated battlegrounds or raids. Of course, you can't grab raid members cross-server yet, much less through Real ID, so it may be a ways off if it's coming at all. Just speculation.