The existence of the used games market is what keeps the prices of new games so high.
When the used games market disappears, you will see retailers and publishers respond by lowering prices, because they have to match what people are willing to pay. Right now they can't match that because used game prices will always be able to undercut new game prices.
Stores like Amazon, Best Buy, Walmart, and Target often offer discounts and deals on new games because, for the most part, their business isn't based on a pre-owned library. Amazon and Best Buy have trade-in programs, sure, but neither of them match the scale of Gamestop's, nor do they base their entire business model on them.
Have you ever seen a specialty store like Gamestop have sales on new games? No, of course not. They don't do it. The only sales they ever have is on their pre-owned library. But when that library disappears, they'll be forced to start offering discounts and pricing competitively, because that's the only way they'll be able to capture consumers.
Look at the PC games market. For all intents and purposes, there is basically no used games market. Digital disto has basically eradicated that. And yet, are games prohibitively expensive? We're all familiar with the deep discounting that Steam does, and other digital retailers often follow suit. Even the new, "unused" PC games are relatively cheap, and it's usually only the multi-platform releases (i.e. the games that Gamestop can influence with publishers over) that are initially expensive.
I realize it's hard to swallow, but the used games market isn't just bad for publishers and developers, it's bad for consumers too. It's only good for retailers; specifically, the one or two retailers that have their massive trade-in programs (like Gamestop).