There's plenty of good new music out there, and much of it is arguably "rock music" even if it doesn't match your rock archetype from the 70s. Yes I suppose it is true that nostalgia rock from 70-year-olds isn't quite as popular as the same nostalgia rock when it was played by 50-year-olds. I imagine there won't be quite as much nostalgia rock from 90-year-olds in the coming years, though even if we're defining "rock music" as a certain set of enduring albums from the 60s and 70s, I'm pretty sure that stuff is still immensely more popular and known by The Kids Today than music from 40 years prior (approximately 1947) was when I was 15.
I came of age where rock-n-roll sort of went from an all-encompassing genre to being being an increasingly narrow category of "rock," with supposed "rock" radio playing less and less music by anyone who wasn't around 10-15 years earlier, and even much of the very popular "rock" music from early days being squeezed out of the canon. Honestly much (not all!) of what sticks around in the minds of people who write about this stuff is the "Dad rock" side of rock from that time, with some post-punk from the 80s thrown in, none of which was the most popular stuff at the time (or since). Popularity isn't a measure of worth, of course, but I'm not sure the stuff that people think was at the center of cultural relevance back then really was.
Anyway, if "rock" music is a subset of music you listened to when you were young plus bands today who try to sound just like that and therefore aren't original, then rock music is dead, almost tautologically. But there's still plenty of good music around that is arguably "rock music" for people who spend the time to find it. Now you can find it (yay internet) but probably won't on the radio (boo commercial rock radio which has sucked for a very long time). I'm old and still manage to go to 6-8 shows per year of music played by people on stage, generally with drums, bass, electric guitar, keyboard, and a singer or two. Looks like rock music to me. Somehow The Kids Today find this music. I'm not sure many people get rich anymore doing this stuff, though there are more potential revenue streams than there were once upon a time to pad things a bit, but bands can certainly find an audience these days in ways they couldn't 30 years ago.
tl;dr if you're interested, there's music out there. old people music is always going to be old people music. what you remember as the best of the best and still listen to probably wasn't nearly as popular and is a lot more Dad Rock than you think.