Its common knowledge that Marvel and DC watch each other like conglomerate hawks; anything that brings success to one, the other will surely emulate. Its been that way since the beginning and its a strategy thats brought massive success to both parties. Since the success of The Avengers, DC and Warner Bros. have been chomping at the bit to pull off a similar feat. Its been reported that Warner Bros. are looking to create a shared DC movie universe (like Marvel did with the post-credit scenes after every Marvel release in the 5-year run up to the Avengers). It also looks like theyll look to begin the construction of this shared universe in The Man of Steel; possibly by having cameos, or at least references to the other DC heroes. A Justice League movie is happening for sure, and you can mark The Man of Steel in your diary as the day they start to build towards it.