Scifi as a space based genre failed due to the end of the space race. The generation that grew in the post WWII era aged and died. The lack of big scientific breakthroughs for the last fifty years added to the lack of new dreams. The future is here, just it's not exciting.

For the last few decades the culturally significant fiction has been in anime and manga. Lots of it is trash, but lots of it captures the ya themes of friendship and adventure. Some of it captured better the ideas of the cyber age, I suppose. If one explores those genres with a bit of background, you can see how they have been inspired by the traditional sf works, but repackaged them for new audiences without the introspection and conventions of yesterday.

I'm not sure if it is all bad. Definitely, science is not an aspiration any more and those works lack the grounding hard scifi taught us. On the other hand, there is still romanticism in those stories and they teach kids to dream for the impossible. I choose to believe that this is still something to base some optimism on.