Plane of Mischief returning as it's own unique zone would be fun. It was a well designed zone, but the revamp took it away from us. So some players never fully got to experience the greatness of this zone. Thank you.
I thought that the original Plane of Mischief files were lost forever and that's why they can't bring it back.
TLP servers get a somewhat rebuilt version. It isn't the same but most of the NPCs are there. You can get all the cards after a serious time investment.