Add Alchemy as a separate thing
Add Alchemy as a separate gamemode entirely, and let historic become the eternal format for MTGA.
Take the opportunity to move the digital only cards out of historic and into historic alchemy instead.
There is only two reasons for why you wouldn't do this; Either you intentionally do this because you believe you can get more money, or you simply haven't understood why an eternal format is needed.
I'm choosing to believe the latter for now. Revert this absolute travesty of a decision, and everyone will be happy, or keep your current course and at least I will no longer spend any money on your game.
I am uninstalling all all platforms until the following two decisions are undone: Not refunding wildcards for nerfed Alchemy cards (a practice Hearthstone has done for years), and not having Alchemy nerfs effect Historic. You lost another paying customer over greed and mismanagement, WOTC. I am not willing to play Historic with these decision in place. I play Historic because it is a Non-Rotating format. Spending wildcards is no longer safe in Historic because of these decisions. You are making cards we spent wildcards on unplayable in Historic due to setting them to an appropriate power level for Alchemy i.e. Standard (not Historic) with not compensation for sunk cos