Unfortunately based on how the CB market has been, a 5th is around what the market says Lattimore is worth.
The real benefit to moving Lattimore is getting any kind of compensation because there is zero chance the Saints keep him on at a whopping $31.4m cap hit next year while they are projected to be $96m over the cap.
Ram retiring and moving on from Lattimore will get rid of a significant chunk of red cap for the Saints. Re-work Carr's contract and that $96m suddenly looks like a lot less of a hurdle.