One person who seems quite open to the idea of a Superman/Batman "World's Finest" style crossover movie is none other than new Superman actor Henry Cavill.
Talking with SFX, the "Man of Steel" star said:
"I think it would be really interesting with the age-old Batman/Superman conflict because they are two different sides of the same coin and their methods are entirely different.
I think it would actually make for an interesting story as to why, first of all, they were going head to head and how. I think that would make a great story. I'm sure there's all sorts of ideas being thrown around at Warner Bros right now.