Tough, they're coming back. Skyjack, starbases DO move and they do kill things. At least in GC1. And now they're coming back.
The reason I'm sounding so sure of myself is because every time I've asserted the matter before, I've then been told it's wrong by a Stardock member. So here's hoping Brad says "Actually, Terror Stars suck, let's not do that". But if you look in some of the .xml they are mentioned, and are (I think) coded but disabled. When the AI is hooked up to them, then it's go time for planet annhiliation. But they will be balanced by 1 move a turn, and the AI going "Dude, wtf!" and attacking you. They also build (and defend) their own. Once I find the quotes I will post them.
PS they WILL return. If you don't like it, tough. (provemewrongprovemewrongprovemewrongpleeeeaseprovemewrong)
PPS Carriers suck. End of.