I would argue that it is taking longer than they thought, but it absolutely is happening.
Name a market in which rock music has gotten larger or stronger.....or even maintained....since then. L.A.? Seattle? New YorK? Hardly.
Name a LOCAL music scene here there are more....or even AS MANY....live rock music venues as there were in 1991. Possibly Nashville and that's about it. And those guys play for tips mostly. Everywhere within 100 miles of me the live music scene is on a ventilator with a weak heartbeat.
Show me the number of rock bands on ANY top 20 lists. Downloads? Streams? Track/album Sales? Ticket sales? There will be a few. But the "other side" DOMINATES in all categories.
Maybe a few legends do OK on tour....Springsteen, etc. All of the "rock gods" have to play festivals or multi-band shows (Styx with REO Speedwagon touring together for instance) to sell out shows. Up and coming rock bands pay to play because there is no money from fans in their markets.
The working "rock" musicians I know of moved to Nashville to take country music tours so they can eat. The most successful "rock" band ever from my area "went country" to hit the charts. They had a few chart hits in that market and still haven't made a career out of it. They were a rock band here for two decades. They toured opening from Lenny Kravits, Stone Tample Pilots, etc. They recorded two rock albums with major labels that never went anywhere. Now they are "country". They had spiked hair and showed their tats for twenty years. These days they wear vests and white dress shirts. Heck, even Bon Jovi, Uncle Cracker, Kid Rock, Aaron Lewis, Darius Rucker, Ween and others have "gone country". Steven Tyler (Aerosmith singer) is recording a solo country album on Taylor Swift's Big Machine record label as we speak.
The guitar is not dead. But it is not as "healthy" as it used to be.....by far. Rock music is in the waiting room waiting to see the doctor for a checkup.
Short version: Show me any proof that rock is maintaining or growing when compared to R&B, pop country and others. I can't find any but I hope you can prove me wrong.
Why does "guitar" have to equal "rock"?
Hint: it doesn't.