To begin, I'm sorry if this is in the wrong forum, I have no idea where this is relevant. If one of my players was wanting to play a kasatha in Iron Gods, what would need to be changed? I've perused the books and can't find anything that inherently breaks with a kasatha pc, but I want to make sure.
I'd say it depends on the character's background. How much does he know about his people's past? Is he part of an existing Kasatha community?
You'll encounter undead and living Kasatha in some of the books, and it will provide a role playing opportunity and challenge for the GM to make sure the NPCs reactions gibe with the players.