Platinum Games director Yusuke Hashimoto confirmed in a tweet back in August that Krystal will not be appearing in Star Fox Zero. He did not, however, express disdain for the character and indicated that he'd be happy to see her appear in future titles.
EDIT: So I didn't look at the date on the tweet. It's from August, before the delay. That said, i doubt they added her in.
Edited by DZComposer