I actually hope this ruling gets reversed. This has been a known factor in physical vs. digital games for a long time. With a physical game, the publisher only makes money during the initial sale. If that person decides that they want to sell their game later, the developer doesn't see any of the money from that sale.
I routinely buy games on Steam when they go on sale for 80%+ discounts. Even AAA titles that are less than a year old occasionally see discounts up to 50%. It's rare that we can say the same for physical games. I expect that part of this is that game publishers have factored resales into the value.
A digital copy immediately has a $0 resale value. It has no further value to anybody other than the person who bought it. But a physical copy still retains resale value, as it can be resold multiple times. Aside from a few exceptions, if a developer sells 100 digital copies, around 100 people get to enjoy the game. Versus selling 100 physical copies, which results in significantly more people getting to enjoy it. Also, physical games degrade, but digital games don't. Without any degradation, there's no compelling reason for someone to purchase a used game over a new one.
Overall, this lost revenue will have to come from somewhere. This will almost certainly hurt indie game studios, as well as the digital storefronts themselves. Epic Games is already far from being profitable as is. I can only assume that this will end in higher game prices, less sales, and lower discounts. Other possibilities could be limits on number of downloads, as that extra bandwidth comes at a cost, or subscription fees for storing your digital game library. Of course everybody has their own opinions, but I'd much rather just keep the games I've paid for, and acknowledge that I can't resell them.