Great Proposal and very well written communicating the idea!
The game desperately needs a card-burning mechanic like this to deal with the crazy oversupply. It would be nice if it could be done with Riftwatcher packs even though it would suck for the ones who went big buying them since values for sure would drop on them and I don't think value of other cards which they own going up would compensate. So as someone who never got into riftwatchers I would vote yes, but at the same time if I had lots of riftwatcher cards I would vote no to protect their value.
I really hope a card-burning mechanic in order to mint new cards or packs is put in place at some point in order to avoid cards getting inflated to infinity. The process of making soulbound card transferable should always include this. Burn common card to mint a common card as one of the requirements and the same with Rare, Epic, Legendary.
THIS.