I just do not see this fight happening if Wilder is paid money to step aside to allow a Fury-Joshua fight to go ahead. It makes more sense for him to make phenomenal amounts of money for doing nothing.
If Wilder is smart he will take the money and then wait for the Fury Joshua fight and then challenge the undisputed champion and if he wins that he will have all the belts boxing has to offer and he can regain his legacy, but as a competitor with big ego i do not think Wilder will step aside because he made a ton of money throughout his career.