I can also think of a few alternatives on where the Skyreaver could've gone-the Glory meta reward, a drop Beastlord Darmac, or maybe just a pure drop from a rare Chimaera in some Iron Horde zone.
It really does suck that the last dungeon mounts were in 4.1. Having a new dungeon mount would be a cool incentive to run whatever dungeon the mount would drop from, because dungeons are currently becoming tedious, and now that 6.2 has no new ones, it'll surely get worse.