Valkyria Chronicles, Lost Odyssey (if it becomes a big franchise), Braid, Portal, and Angry Birds. FPS's, big franchises like RE5, and such tend to overshadow themselves. It's these young upstarts that people are going to remember.
Of course, every Mario, Zelda, Donkey Kong, etc. will bw remembered as timeless classics. It's their gameplay that make them immortal. Games like Uncharted, Killzone, and Call of Duty will be forgotten as the next big thing pops up. They rely too heavily on presentation. Then aggain, 20 years isn't a very long time. I can remember tons and tons of games from the 8-bit/16-bit era.....








