I am basing my expectations on the pricing on XBox Live. The XBLA stuff fluctuates and there's been a couple of sales (got El Shaddai for ~2$ so I know it's non-zero), but mostly everything stays pretty high relative to what the market can bear. If they change behavior, so be it, but let the record show it's not groundless speculation; the digital download market for Xbox 360 has been around a while.
It's true that we can't speak on how pricing will work for Xbox One games, but we can certainly comment on consumer opinion regarding the inability to lend games out on Xbox One vs. Steam.