Casting has already begun for the upcoming Guardians of the Galaxy sequel that is being helmed by James Gunn. The Marvel shared Universe is a large success which has others following pursuit. There are now plans to bring forth the DC Cinematic Universe, and even a Transformers Shared Universe ( which G.I. Joe could have been a part of). Avengers: Age of Ultron is already a billion dollar earner at the box office.
The first Guardians of the Galaxy film was an interesting take on the characters, as Ricardo Tosto points out. There is already a 70 page treatment available that is the starting point for the sequel. Principal photography begins next February for the upcoming sequel.