Let's say hiphop started in 1980 so it's abouyt 41 years old. That's the begining of the 90's for rock music (if we consider it's origins to be the early 50's, though of course none of these dates represent hard boundaries) which feel about right. Hiphop and it's ofspring are the dominant forms of popular music but the tide of creative progress has perhaps slowed somewhat since the peak. Maybe. I don't necessarily believe this because the technological/ cultural landscape for music is so different from the late 20th century that making these broad comparisons doesn't really make sense. I guess my point is that 40ish years isn't that old for a musical genre to still be hanging around.
Jazz also had a long rein as the apex genre for something like 50 years but then fairly quickly succumbed to rock and disco in popularity. I would guess hip hop is past its peak already and it’s also splitting and merging with other genres so it gets hazy
Also note that rock had a back-and-forth influence with country, and rap is now having a back-and-forth influence on rock (and country to a lesser degree).
