Here is a link about the decline of rock (used as a generic term):
https://theweek.com/articles/861750/coming-death-just-about-every-rock-legend
"Rock music isn't dead, but it's barely hanging on.
This is true in at least two senses.
"Though popular music sales in general have plummeted since their peak around the turn of the millennium, certain genres continue to generate commercial excitement: pop, rap, hip-hop, country. But rock — amplified and often distorted electric guitars, bass, drums, melodic if frequently abrasive lead vocals, with songs usually penned exclusively by the members of the band — barely registers on the charts. "
While it focuses on the age of most superstar rockers, it also talks of sales declines.
https://theweek.com/articles/861750/coming-death-just-about-every-rock-legend
"Rock music isn't dead, but it's barely hanging on.
This is true in at least two senses.
"Though popular music sales in general have plummeted since their peak around the turn of the millennium, certain genres continue to generate commercial excitement: pop, rap, hip-hop, country. But rock — amplified and often distorted electric guitars, bass, drums, melodic if frequently abrasive lead vocals, with songs usually penned exclusively by the members of the band — barely registers on the charts. "
While it focuses on the age of most superstar rockers, it also talks of sales declines.