What about the logistics of bringing back older sets already on Arena? I'm dying for Amonkhet sealed/drafts. And as much as I'd love a mastery pass/God avatars/sleeves to go along with it, that takes extra resources beyond a set that was once on the platform. For the cards themselves, how much work would that be?
For rules correctness, the work for the sets that were in the Closed Beta is almost nothing. For getting the quality of those sets to match that of those that are in the live game, there's at least a couple weeks of work. But the big hurdle I think is in answering the question "what's the best way for players to get access to these cards", which is a reasonably tough question that happens to be entirely out of my domain. #wotc_staff