To be fair, Carrie is the only person Saul has. He knows which buttons to push on her to do things or trigger certain behavior. She was a UI, right. But only because she is good at what she does (if you see the mission outcome on the whole, not the way to get there). The Russians used her to saw off Keane, although Carrie was only a citizen with no agency help in the background. This shows her value in the spy world. Saul knows this. She just got Dante to talk, which he probably never would have achieved without her.
I agree that she couldn’t trust her own mind at the end of the last episode. But I think she will be less worse off after she has accepted that Franny is safe at her sister’s. It’s sad, but a great burden might fall down if she hasn’t the responsibility with the child anymore. That’s what she can tell herself to feel better and what others will tell her. On the other hand, the outcome of the custody battle could go just the opposite direction and the guilt and feelings could kill her. But Carrie is Carrie, and will function. So I’m going with the first possibility.
I’m not sure if Saul can adapt to Carrie’s situation and reflect on where she is right now to empathize. She’s in a fucked up mental state. I think Saul will use his charm, give her the opportunity of an interesting mission, and she’ll take up his offer.
The probability of failing miserably, which might end in her death, is postponed to the end of season eight IMO.