Not even a week after DuckTales: Remastered was removed from Steam, Grid 2 has followed it into the memory hole. Codemasters' racing game presumably had to be removed from sale for the same reason its predecessor did a couple of years ago—expiring licenses, either for its car models or the songs on its soundtrack.
Grid 2 was given away on the Humble Store in March, and the previous Grid was offered for free before disappearing as well. That's a nice way to go about it, making sure as many copies are out in the world as possible so that the historically minded can preserve them. It's certainly better than simply having games vanish out of the blue one day, as recently happened to Sega's spy RPG Alpha Protocol.
As is usually the case with Steam's delisted games, anyone who owned Grid 2 already will be able to download it in perpetuity. The next game in the series, confusingly called GRID, will be out on October 11.