I didn't say refilm Miller's footage, I meant cast a new actor for the character's future appearances. After the Flash movie is out and they want to bring Barry back for a sequel or guest appearances in other movies, just pull an Edward Norton/Mark Ruffalo or Terrence Howard/Don Cheadle and they're good to go. Marvel didn't just drop the Bruce Banner character because of issues between the studio and the actor, they just recast the role. Similarly there's no point for the Barry Allen character to suffer because the actor has been a fool. They can cast someone much better suited for the part than Miller anyway and who would actually have their act together.