Matthew Stafford signed a 5 year, $135,000,000 contract with the Detroit Lions, including a $50,000,000 signing bonus, $92,000,000 guaranteed, and an average annual salary of $27,000,000. In 2020, Stafford will earn a base salary of $7,800,000 and a workout bonus of $500,000, while carrying a cap hit of $21,300,000 and a dead cap value of $32,000,000.
Detroit would probably have to trade Stafford and make it extremely attractive for the other team to unload him. GMs generally don't want to take on cap hits of that sort of magnitude. While others speculate, most likely scenario is that Detroit keeps Matthew Stafford at least for another year.