Here is my proposal:
Yordan Alvarez, Rogelio Armenteros, AJ Reed, and Brian McCann
For Realmuto and Prado
The deal gets the Marlins two very good Cuban prospects who they can market to the Cuban community and they get out of Prado’s contract. McCann goes to the Marlins to offset salary for the 18 season, but Marlins save a lot in 19.
The Astros get their catcher for the next three years and maybe Prado is a useful piece, particularly if they lose Marwin to free agency at the end of the 18 season.