Bringing my previous answer back:

Unfortunately dev work isn't done for those sets anymore. They were in the game at one point, but due to so many things changing in game, the team would have to completely redo them. Then they'd have to go through testing (with additional testing this time because more cards).

Would it be cool? You bet! I'd love to have my precious Anointed Procession back.

@ChaosKnight#75971:

Lexie, are the devs planning historic drafts as events in the future and any chance they have plans for sort of a mini chaos draft in the future? where its 3x of 8 different sets instead of the 24 different sets?

This is what we're working on right now: