Were the “new” 4 classic cards a replacement for the spells that rotated?
If that was the case, you’re only considering this for class cards, or do you have something thought for rotated neutral cards like the oracle?
If that is not the case, could any cards from other sets be reintroduced in standard, like rogue secrets from kobolds or whizbang, or the amount of cards in classic is just limited to the number it had originally?