When the achievements system comes to TBC/Wrath Classic Will there be like cross-progression/rewards. So say you play Wrath Classic and get the Nax meta you get the mount in retail. I think it would be a amazing way to bring back old mounts/mogs that are long gone.
I fully plan to play TBC Classic and in the future Wrath Classic. If they was to add this feature I would play both non-stop.