The Atari 2600 is a system that younger collectors/ retro gamers do not show much interest in, most know of it, with ET being the most well known game on it, but NES tends to be the farthest back younger people go, unless they are hardcore, or find one cheep at a tag sale. (Judging by me being in high school and knowing what my retro-gaming friends are into)
I doubt prices will go up on average games, but the land fill carts might be worth extra due to them being part of the ET legend.