The pair would do well not to burn bridges - as the market, for commercial royals, is uncertain. Will a British royal and an American TV actress (add former, to both) be in demand - as a duo?
Probably the closest comparisons are Simpson/Edward8 and Kelly/Ranier - though in different, and pre-internet eras. S&E didn't go too well.
However K&R seemed to have a good time - living in the US, France and Monaco, whilst rearing a family. That is - until Kelly's sad demise in a tragic car accident.
However - as Ranier was the head of the illustrious, ancient, aristocratic and extremely wealthy Grimaldi family - neither he or his wife had financial concerns.