The intro in the 20th-anniversary reprint of Psion says she's got plots in mind for three or four more Cat books.

Thanks! I didn't even realize the anniversary reprint existed; I discovered (and later acquired) "Psiren" in her collection Phoenix in the Ashes (1985).

Apparently Vinge has had chronic health issues -- fibromyalgia and the aftereffects of a car accident -- that have put her writing on hold for the last few years, so she's probably got a lot of backburnered plotbunnies to catch up on now.

Yikes. I am glad she's recovering.