and the Millenials are slowly fading away from the gaming landscape entering the parts of their lives where wife, children, career etc. become more important.
Once a gamer I think you will always be a gamer, eventually you do find some time for yourself, else you go crazy. But I do think that once the things you listed come in the equation, you start being more into single player games, that you can play at your pace and for which you dont need to play 12h a day to keep the muscle memory up in order have a chance against the kids.
So while I doubt they drop off gaming totally, they do probably start to drop off multiplayer games, barring I dunno, maybe 1 night per month with the squad in Warzone?
There are multiple reasons obviously, its even in the article. One I would like add is (and I honestly take no pleasure in this, as its also the stuff I've grown with also) that I just think arena shooters are dying, or at least the mode. How many decades can you play the same 3lane small map where the one who sees the enemy first is the one that gets the kill ? We need something new honestly. I think Halo is fine as it fits a special niche, its a bit more slow, the ttk is higher because of shields etc, but for the rest eh. Like lets be honest , something like Medal of Honor reboot (2010 + Warfighter) would get massacred in today's market.
This is also exacerbated by the iNfLuEnCeRs pushing their BR agenda to the kids that follow twitch/streams.
I think next COD will sell a bit better because MW reboot was really liked, but after that I think the francise will drop again to this level of vanguard, maybe even lower.