Really though? Seems to me that the only sub-genre of space science fiction that is surviving relative to others is hard space science fiction. There's an abundance of high quality titles to choose from even (compared to the previous millennium).

Edit: Highlights include Leviathan Wakes/The Expanse, The Three-Body Problem, Children of Time, Pushing Ice (and other titles by Alastair Reynolds), Interstellar (debatable, but it's good), Project Hail Mary, For All Mankind, and many more.

Which is unfortunately true, but also just illustrates how far science-fiction has fallen - not sure when it started but I guess Star Wars played an important role to remove the 'science' from 'science-fiction'.

Technology sufficiently advanced is indistinguishable from magic, after all.