This seems pretty realistic. We're at a point where most people have more entertainment than they know what to do with. Between listening to music, listening to podcasts, reading novels, comics, watching anime, movies, binging entire series on streaming services, watching video series on YouTube of game streams on Twitch and actually playing games, people can afford to be more picky about how they keep themselves entertained. If everyone chases GaaS, that trend will fizzle like any other.
I also think it's just about quality over quantity, too. As I mentioned above, most of the GaaS titles provide such a sort of homogeneous, carefully metered amount of "fun" that they lack a lot of high-highs and low-lows of shorter, more carefully designed games. I suppose I could play Destiny or the Division for 1000 hours but at some point I am playing out of habit rather than active enjoyment, and like you said, there are so many other options that offer a more condensed feeling of fun and accomplishment.