First off, I know this is beta and I know things change a lot. None of this is set in stone at the moment but I just wanted to clarification on this statement.

Quoted from Mumper

"(note that all guild achievements start on Cataclysm launch, so anything you have now will not matter, it must be done with your guild after launch) "

Does this mean that we will need to go back to these instances to complete acquire these legendaries after the implementation of guild achievements? If yes, I'm assuming this is a way for Blizzard to keep people going to the old raid instances to keep them from falling by the wayside.