Cards are already soulbound. SPS rewards are very little for Gold League and under.
Then the very steep requirement for Diamond and up where people are already investing in maxed out cards which is very expensive.
This development cuts off new demand for maxed out cards.
Yes, it might initially, driving their value down. The lower the cost, the higher the demand, right? Currently, the value of cards is in freefall because of the constant release of new sets, without demand to buy, at prices that would have been high during a bull market, whilst in a bear.