I really like the proposal, and I like the concept of the DAO making money/amassing assets from which to pay out future rewards. I would not be in favour of burning the vouchers. There is no need to burn them IMO as they would be taken out of active circulation at this current period of oversupply.
One amendment I would suggest would be the purchasing threshold, which needs to be linked to the card rarity and average SPS holdings of players in different leagues. Under the current proposal in order to have the right to buy a maxed card, if common, would require holding 400k SPS. Currently, only the top 197 players' accounts hold enough staked SPS to qualify to buy a maxed-level card. The rate of one voucher per 1,000 staked SPS sounds OK, but it would perhaps need to be a legendary or epic-level card.
RE: SPS DAO Mints Promo Card for SPS Stakers