Fear and Gibson have only won one world medal, and I just can't imagine they want to end their season with their free skate at the Olympics. I'm sure they want a chance at a redemption skate.
Charlene and Marco, I can absolutely see them wanting to end their careers at their home Olympics. I could also see them wanting a third world medal, even if it's not gold, but, depending on who goes, there could also be a risk that they wouldn't medal, especially considering that I'm sure they'd be exhausted.
Piper and Paul don't sound like they are going, and I absolutely wouldn't if I were them. If they had a chance at a world title, sure, maybe, but their free dance was a perfect moment and it seems like the moment to go out on.