When I saw Days of Future Past the lights came back on during the credits.My old cinema used to turn off the screen shortly after the credits started, usually when everyone had left. Hated that. Especially when there were films that had scenes playing over the end credits like 'School of Rock'. Granted, I was the only person left but all that changed when Marvel started doing post credit scenes and annoyed parents had to ask staff to restart the credits because their kids wanted to see the post credits scene. Thank you Marvel.
(temporarily)