I just bought a new pistol yesterday in .40 S&W. I like it. But then, when all my buddies in Junior High were Chevy fans, I bought a Ford as my first car, just to be unique. I hate following the crowd. The .40 S&W is bigger and ballistically superior to the 9mm. But I carry a P365 in 9mm due to the size, and because I believe statistics that show they are both very, very close in effectiveness.
I think .40 S&W will remain relevant until the majority of it's fans start dying off. Most .45 ACP fans are in their 60's, 70's, and 80's. They are not long for this world. My dad is 83 and never owned a 9mm or a .40 S&W. Nothing but a 1911 in .45 ACP, or a .357 Magnum wheelgun for him.
I'm 50 and love .40 S&W. I grew up with it as one of my early carry guns in my 20's. My son and son-in-law love 9mm. They are in their 20's. I still love them, though. LOL.
Caliber war threads are interesting because they are such a mix of science, statistics, and emotion.