The referenced four inspirational chords are from Link Wray's instrumental Rumble: https://youtu.be/RLEUSn8y9TI
There is also a wonderful interview on Audible by Bob Edwards with David Guggenheim the director of Might Get Loud on August 21, 2009. I have it on audible, but unfortunately I can not locate it on a Public Radio archive to share. If someone can find it, please share.
Four Chords in Rumble https://tabs.ultimate-guitar.com/l/l...e_ver2_tab.htm
There's actually a very nice pentatonic run as the turn around.
D, E, A, B7 or D, Em, A, B7 What heck is that?
IV, V, I, ii ?
Vii, I, IV, V ? ...
As Mr. Booth pointed out every long lived industry goes through cycles. One datum that is pointed out in the article is that the current sales zenith was 1.5M and currently sales are just over 1M (1.5M > 1M). The article attempts to reflect on some of the reasons for the decline by talking to some industry execs and surveying the current popular music trends. Nothing fake, just observations and possible conclusions based on those observations.