The Parasyte manga ran from 1988 – 1995, Yet the anime was adapted in 2014. So there is still hope!
Except Parasyte is a critically acclaimed seinen action that at least can attract an audience and sell something while Octave is a virtually unknown yuri manga. Unless the yuri genre actually becomes mainstream, it's not gonna get that same treatment easily :/
Well, even some very old manga like Toward the Terra (1977) eventually got their anime adaptation (2007) so I wouldn't say there is litteraly no hope. But I concede there isn't much, sadly.
We'll have to bear with what we have animated : some really shitty yuris. But if this can help expanding the genre then it's something we should be happy about, because it could lead in the long run to the adaptations of some really great yuri. (Hanjuku Joshi, Gokujou Drops, Octave, Girl Friends...).
... I'm not giving up ! One day, the yuri will rise.