Through all the GC versions, I've mostly avoided conquest wins in favor of diplo, tech, or ascension. Lately, I've been trying out the aggressive side of the tracks, and I finally destroyed the Drengin for the first time.
When I did that, all of their assets (ships, yards, bases) disappeared from the map. Every other time I've destroyed a faction, their assets have turned over to me or an AI or gone pirate. So the disappearing thing was startling. Next turn, it was followed up by a very weird thing. I got a surrender-to-you message from the departed Drengin.