if it returns, Samantha
I wonder how they'd address her absence, since they kept rolling out the red carpet for her, but it won't happen.
I think they'd say she and Carrie made peace and are friends again, so we'd constantly hear about what Samantha's up to, but since KC wouldn't want to return, they'd say she just enjoys London so much she's staying put there, and so we just get occasional tidbits and she becomes and off-screen character. On one hand it's lame but on the other I really can't think of a better way to handle it