Most game makers are targeting consoles, which just went through a longer than usual shelf life. With the new ones coming online, we will see more PC upgrades from gamers.
High-end for 4:3 was 2048x1536 (3 megapixels)
High-end for 16:10 was 1920x1200 (2.2 megapixels)
High-end for 16:9 was until very recently 1920x1080 (2 megapixels)