My guess is if that happens, studios will choose not to put their games on sale anymore or less frequently. Why would they discount the game when the used market is an option. It also depends on the average price of the game used and if a sale undercuts the used market. Lots of variables and there’s opportunity to boost new sales in the form of perks, bundles, exclusive in game content, etc…
Check out protondb.com/ to see how compatible a game is with the deck (and Linux in general). The comments will usually have suggestions for getting the game to run well.