When it comes to media/entertainment, people say "the era of X" is dead all over the place. Not to pick on you, but they're usually wrong. The democratization of fiction publishing has made it so that any X where there are consumers can exist.
Go look at the Kindle Store and how many "true Science Fiction" books are published every month. They're there. You just have to look for it, same as every other catered niche.
Yeah, I think we're now in the era of curators. Since it's much harder to find good books in a particular niche, it would be really nice to find a good trusted curator to weed through.
If you're fiending for good hard sci-fi check "The Expanse" or the "Remembrance of Earth's past" trilogy. Vernor Vinge his "Zones of Thought" trilogy is also great :)
Go look at the Kindle Store and how many "true Science Fiction" books are published every month. They're there. You just have to look for it, same as every other catered niche.