I wonder if this will retroactively go back and add something like League of Legends to your account.
I know Valves payment policies were different them, so it probably won't happen.
The applicable games are automatically re-added to your library, even if they are no longer available; for example, I have Battle for Graxia in my list despite the game being shut down a couple of months ago and consequently pulled from the store. LoL, from what I can gather, had no DLC on the Steam store, so it's not covered by the change.