As for GameFly, I'm assuming that there will be separate "rental only" versions of the game similar to how VHS tapes were handled back in the day. My uncle owned a rental store, and I recall him telling me how a VHS tape would cost around $100 rather than the $10-20 you'd see in a store. That was mostly a license thing, but I'm guessing a higher priced version without the code requirement could be sold to rental places.
I think the more annoying aspect of this is that it tends to lock people down in other ways. For example, I can't just bring a game to a friend's house and play online without having my own profile. Well, I can... but I'd have to pay $10... when I already own the game and said "right" to play online.
I'd actually like to see some monetary justification for these fees. I've never really been a fan of a "flat fee" especially when the company can just go and say, "we're ending this service in 30 days" the next day. Aren't most of these online services really just matchmaking services anyway? $10 seems a bit steep for that. Overall, I'd just like to see some sort of proof that these players purchasing used games are actually taxing the system enough to require $10.
I highly doubt we'll ever see that.