Exactly this. Also for all of us that have kids, being able to use that massive screen for entertainment as we wait to pick them up or for those who have spouses, would be great to be able to wait in the car as they shop and we watch a movie with the Model 3 surround sound and AC on. Hardware is already there so why not!
Maybe on Wifi, but couldn't see them wanting people to stream movies on Netflix over the car's data connection.