older cards could, theoretically, lose some of their market value.

I hope this doesn't become the case. I know that there's an urge for conclave to sell a lot and this is fine, but if some of the newer innovations like the bloodline thing, then it means more cooler cards will come out in 2 to 3 years time and devalue the current set, then the the cycle will continue, there has to be a sort of balance.