Glory of the Raider rewards to go away in 3.1

It looks like we'd better get a move on if we want the special mount rewards from raid achievements. They'll be going the way of the Amani war bear once Ulduar and its gear become available. The achievements will remain, but the tangible rewards will not.

When do they go away? Rather, when is 3.1?

3.1 just hit the PTR, and it's a big content and class change patch, so I'd guess it will be a couple of months, but that's a wild guess.