I'm gonna guess Cage will be fine. I hope I am correct. I think Cage has been teh sort of actor that refines his craft over the decades. he started out being the same character over and over (Nick Cage is this.. Nick Cage is that.. always basically being the same person).. but I think he's gotten better. Since anyone who'll watch this will think they know John Madden.. this will be a great test.. will it be Nick Cage is John Madden.. or will it be John Madden being played by a talented professional actor.
Pretty soon.. actors may basically just be voice-actors in motion capture suits with AI-CGI taking their motions and voices and mapping them to, say, a near-perfect 3D model of John Madden or any other character.. and use the actual persons voice saying what the actor said and how they said it. They can do it now.. but you can see it's not right.