Psst, that's how it got between the first young rock stars (Buddy Holly, Chuck Berry, Little Richard, Jerry Lee Lewis, Elvis, etc.) being either dead, prosecuted, drafted, or otherwise knocked out and retired and the Beatles "coming up".
Bobby Vee, Bobby Vinton, Bobby Darin, Bobby this and Bobby that (as Jerry Lee Lewis put it).
There are rock and roll acts today but they can't get promoted by the majors or by radio.
The suits ushered in the return of late-80s style boy bands and girl singers to push the grunge/indie thing off the charts. "That fad is OVER!"
Not so much dying out as losing their old audiences. The crowd that started listening to rockabilly are starting to disappear and haven’t paid attention to new music for a long time.
I’ve got pretty wide ranging musical tastes but the my first favorite heavy metal will will eventually fade too despite still filling stadiums with people 30 years my junior.
As far as rock going away, I’m not so sure despite the crap like hiphop and rap that gets airplay these days. Kids find a way to listen to more alternative stuff than top 40s crap. Black Sabbath wasn’t getting much airplay in the 80s but I still ended up with all of their music.