Ah, interesting, thanks, DTO.
It was already known that the subsequent Bryne reboot would eliminate all Kryptonians except Superman, the "Sole Survivor". So Supergirl simply HAD to die, and thus she was on the top of the Crisis "hit parade" from Day One. In contrast, Marv admitted to me that he was surprised when DC asked him to kill off Barry Allen -- that casualty was rather unexpected.
What exactly is the timeline on the reboot and Crisis and all that? As in, how early was it that they decided to go with Byrne for a reboot, when the ideas that became the reboot formed, and when was CRISIS planned?
Because I get a definite feeling that CRISIS wasn't planned out with knowledge of the Byrne reboot in advance - for instance, Superman seen after the worlds unite in CRISIS #11 was clearly the Earth-1 Superman. The whole business with Wonder Woman and her Crisis fate implies they knew they were going to do something with her, but if they wanted to do a Captain Marvel reboot, why is it Captain Marvel was shown in a panel on the reunited earth?
According to Marv, while Supergirl was a familiar and much-beloved character, many of her most ardent fans fondly remembered her Action Comics days -- nearly a quarter century before the Crisis. These older fans weren't the demographics that DC was aiming for at the time, while the younger readers who bought more comics weren't so strongly attached to Supergirl. (And thanks to DC producing some truly wretched Supergirl stories, Kara was seen as being unable to carry her own title.)
I don't know if that's entirely fair of the Big Bad Wolf to say. Supergirl had some pretty good stories in the SUPERMAN FAMILY book in the seventies: for instance, that one by Elliot Maggin where she fights an Aztec Princess after she moved to Florida. And that Legion story on Weber's World with the Emerald Empress in the early eighties.