I've been wondering about how our era of media will look in hindsight. It feels like we're in a weird place where media products now are so high-fidelity that they won't "age" in the same way that stuff from last century did. Old movies, old recordings, old photos... I was watching some Marx Brothers stuff with my son and realized it was about 90 years old, and it looks it. It's decrepit. I have some recordings from the early 1900s that sound like they're echoing down the halls of time. 200 years from now, people will be able to watch our TV shows and count the pores on someone's face, and hear every polished whisper on every pop album. I'm sure stuff will feel dated as fashions change, and new technology will make what we have pretty outmoded, but everything is so available and so accurately reproduced that we're just kind of drowning under the weight of it, and all those peculiarities of media from the past are available now as stylistic choices for new creations. You can get that 1960s film quality or that 70s drum sound. It's no wonder people look backwards under these conditions. And I think the concern with "authenticity" in a lot of metal creates another pressure to look backwards.
Having said that, I do think there's new stuff happening, even if it's only incrementally new, even if marketable retro heavy metal and thrash and throwback DM and 2nd wave nostalgia acts are everywhere you turn.