I dont think it will go that low so to say, but yes it would severely undercut retail cost.If this is going to sell like their market, than you are going to see prices of 0.1$ per game, since just like you, there are thousands of people wanting to sell the same games they bought through packages.
The biggest immediate issue would be how this impacts the retail sales. We have platforms with 10s of millions of users, these same platforms would need to market the "used" title. I could easily see where end consumers would be in situations where they would no longer really ever need to buy a game at retail value even as early as 1 month from release particularly for single player games.
In time depending on how this plays out, this would/could push the market more towards gaming as a service delivery. Which is largely where the software market has been for years.