Nah I don't think so...the big, important games won't be forgotten...I remember when I was really young, I had no idea that star wars had 4, 5 and 6...I had only watched the first one. I didn't know about Indiana jones, Halloween, Jaws ect. My dad was the one who told me about them, just like he told me about his first games, asteroids, tetris, donkey kong and others. I didn't know about old movies, or games, neither did my elementary classmates as far as I can remember, but now that I'm a bit older people my age know about the classic movies, and games.
Today those older movies are not known by most younger people, they don't go out and watch old movies or play old games for the most part....but the best movies and best games are not completely forgotten.
Of course some games will be forgotten completely, just like some movies and some books have been. If I had never heard of all those old, successful landmark games from the 70's 80's and 90's then yeah I would say games from today would be forgotten, but that's not the case.