Speaking of what I just linked, thinking on it, that may be the kind of sound that evolves into normality in this alternate reality. That being a kind of folk with psychedelic and garage rock thing. Not the only genre, of course, but a more common sound perhaps. (I don't think it was non-existent as it was).
EDIT:
On the topic of genre and popular music evolution, I do think it will have to break out of the confines it was placed in circa 1963, just before the Beatles did hit and the British Invasion followed. The British Invasion was what broke music out of those confines in the OTL, but it seems like there would have to be something else that would do that in a few years anyway. Nothing artistic ever exists within limitations. That's why Folk evolved into Folk Rock: artists got tired of not being allowed to go into certain territory, of having to have a certain way of dressing, of only dealing with certain subject matter, and so forth. That's why Glam Rock died; it burned itself out and became a parody at a certain point.
And there's the factor of backlash as well. We have gone into the fact that the first generation of Rock n' Roll was largely taken out by the late 50s, and Rock had become all too much label controlled with artificially created artists pumping out singles about girls and cars for quick teen money. It's the Dark Age of Rock. That's not fair because there still was a lot of good content, and there still were artists who were very good, but there certainly was that proto-boy band element of astroturf artists. That doesn't seem like it can exist forever. I think people would have backlashed against it or increasingly ignored those artists and groups, and that they'd go to other groups that weren't astroturf, possibly like how Indie Rock and groups in it like R.E.M surged in popularity in reaction to the 80s Glam Rock and Hair Metal (etc) Rock scene of the 80s. Or rather than an insurrection from the Indie, it could just be someone else being discovered.
I'll bring up Folk, which could have still evolved into Folk Rock and infused into the alternate American Rock sound from there. And Garage Rock is a possibility as well, which would mix in with the American Rock scene and eventually blend into that mixing pot. And then it evolves from there.
On another topic, I also think Black artists and genres could do better in this alternate scene compared to the OTL (and those genres were big in the OTL nonetheless).
