So….the Wal-Marts in my area have very, very small video game sections as it is, and knowing how valuable real estate is in a store, My assumption is that the amount of new stock they carry is going to shrink substantially. Additionally, i'm guessing there'll be a very specific list of games they'll accept, lowball you as bad as Gamestop on trade-in value, and use a very similar pricing structure to Gamestop on their used prices.
You're going to see those discount shelves with 2+ year old games swapped-out for shrink-wrapped used copies that they can get a higher margin of return on. Makes sense from a business standpoint.