There are two cases of games that become 'classics'.
The first case is that of extremely popular games (Pacman, asteroids, duckhunt, tetris...).
The second case is that, despite selling much less, they left a huge impact on a smaller group of people (Monkey Island, Zelda...).
Some games were popular AND left a huge impact (Mario, FF...).
So I think huge selling franchises will be considered classics in the future. CoD, Wii Sports, Kinect, Gears... and a few continuation of sagas of which all games sell gazillions and are considered classics: GT5, GTA IV+V...
The games that will leave an impact over time are more difficult to guess because more perspective is needed. I'm sure that games like MGS4, Skyrim, Mass Effect... will be remembered.
No troll is too much for me to handle. I rehabilitate trolls, I train people. I am the Troll Whisperer.
