deathtokoalas
i think you're confusing popularity with youth culture, which is something the industry does, but it's important not to get too lost in it.
the decline of rock music has as much to do with industry decisions to phase rock music out as anything else. pop music is generally very pro-establishment, pushing the kind of consumerist messages that the status quo wants. rock musicians have historically tended to mess with that. the rock of the 90s ultimately failed, but it was on the cusp of getting people to think very differently about a lot of things.
even with that said, the truth is rock music has simply gone downhill. it's not hard to understand. if you're a creative person born after about 1980, you're naturally going to look more to technology as an outlet. that doesn't mean a demographic for new rock music doesn't exist, but it is leading it to a warping of the rock form. ultimately, stuff like st. vincent or even lorde is fundamentally still rock music.
the above list is a list of gen x music. it all still sells pretty well. but, it's mostly older people. understand this: tom petty just topped the billboard list, and his demographic is mostly in retirement age. he didn't get a 50 million hit video on youtube or massive radio play on the pop station, but he did sell more records that week than anybody else that did.
i think there's still some room for innovation in rock, and i don't think you've seen your last rock star. techno (like disco before it) seems unable or unwilling to address more complex subject matter. so long as that remains true, people are going to continue to default to the rock form.
