Any platform that offers transferable digital licenses will get a lot of customer loyalty but is likely to have mainstream publishers boycott it.

It could be structured so that everybody wins e.g. the purchaser pays ⅓ less than the “new” price, with their payment then split evenly as cash for the original publisher and store credit for the seller.

That way:

1. the purchaser gets a discount
2. the publisher gets a cut of the sale
3. the seller gets credit to spend on new games,
4. the platform gets that credit spent on their store (plus any additional money that might be required to complete a purchase)

As a customer I would find that attractive but I think most publishers would consider it a slippery slope.