Interesting article from a law firm on the legal position or case for a 'divorce' payment -
https://www.dlapiper.com/en/europe/i...-legal-issues/
Basically, there's no legal basis or precedent for a final payment but there are some unanswered issues about payments that need to be clarified (Nigel Farages pension for example) It seems the decision of whether to pay and how much is a political one.
One point to consider going forward is how the UK will appear to counties wanting to set up trade agreements if it appears to walk without addressing ongoing commitments.