bystander :
Every new generation of cards, we get people excited that their new card can play 4K without lowing much if any settings and within a few months, they are back to the same situation as always. The top in cards are generally good to go at 2560x1440 with only some reduction of settings and will remain that way for generations to come.
The cycle is very consistent;
1) GPU manufacturers make a faster card
2) the game developers make more demanding games.
Developers prioritize developing games for consoles such as the PS4 and XB1; they earn a living by selling games and to maximize their sales, they design games for the systems the majority of gamers possess. For those with above average systems, they can increase the game settings.
Most PC gamers are casuals and most average casual gamer will not spend $1000 or more dollars on a single GPU; my guess is that gaming enthusiast (gamers who spend $2000+ on their gaming PC) is outnumbered 2/10. The data easily found by looking at Steam's stats for their customer's hardware. Only 1.5% of Steam gamers possess the 1080 Ti and 1080p is dominant.