There will never be a dearth of science fiction material in the self-publishing realm. The imaginations of self-published authors are infinite and infinity is probably the ceiling for the number of science fiction books that will ever be self-published.
And this is great for the reader.
Imagine so many ideas and so many fantastical worlds that could well be out there. These books combine to create a world far greater reaching and with far more opportunities for adventure that any one individual could imagine.
Here are some of self-published Science Fiction offerings from AuthorHouse. http://www.goodreads.com/shelf/show/authorhouse-science-fiction