So a guildy had sad something about this too me, so I decided to check it out during a flyover for Archaeology. I would post screenshots I took but I havent made an account to post until now. :P Either way, at the top of Karazhan's main tower there is a small balcony with an unmanned griffon roost and a caged/gated off (No tooltip upon mousover) green instance portal. This isn't the back entrance, and I confirmed that the back door was indeed still in the same place. I'll have to make a run through Kara to make sure its not just an exit, since we could fly away now.
Just thought it was interesting, possibly bringing Kara back or popping a new boss at the top? I really don't know, but what do you guys think?
*Once I gain more posts I'll post my screenshots if no one else has at the time*