First, Blade Runner did NOT do well in theaters. It was a flop. It attained true cult status and made most of its money later on video.
Second, Mr. Scott is talking about Hollywood Sci-Fi which, since Star Wars, is made for the obviously sole purpose of making money.
These days, not many Sci-Fi films aren't blockbusters or aren't conceived as such. Most of these films have huge budgets and so are marketed as blockbusters in order for the studios to make some profit. So we almost always get dazzling special effects as the lure.
They're not dead but as with all the other genres in Hollywood, they need an infusion of original, creative thinking. They need to be written by writers and directed by directors, not rewritten and directed by producers.