It has been rumored that there is a crossover between Avengers and the Guardians of the Galaxy. As to its authenticity, none is sure. According to a recent post by the Christianpost, "It might still be a while before fans can get to see 'Avengers 3: Infinity Part 1' however, speculations are already rampant as to what fans can expect from the film." Marvel enthusiasts discern that the third installment of Avengers will be the Phase 3 of the studio's vision of its cinematic universe. This clear shows that superheroes will soon be assembling.
It was also rumored that Hulk will be fighting off supervillain Thanos in outer space as stated in a report by Ventura Capital Post. There is much more to come for both the Avengers and of the Guardians of the Galaxy series. Actor Jeremy Renner whose character is Hawkeye in the Marvel Cinematic Universe pointed out to in a clear statement reported by the Christianpost, saying, "Is that going to happen? Do you know more than I know? I think they'll probably do another Guardians movie, and we still have Avengers 3 and 4 to do."
It seems that the fans are torn as to what will be the outcome of the plot, it appears that more mysteries will remain as such. However, based on a report by the Christianpost, "Fans can expect that other Marvel characters are going to be introduced in the movie, such as Doctor Strange, who will be played by "Sherlock" actor Benedict Cumberbatch; Black Panther to be played by Chadwick Boseman; and Captain Marvel, which has not been cast yet."
Other known characters that will soon be added are Emily Blunt who is rumored for the role; The Inhumans, Tom Holland's new portrayal of Spider-Man as well as Quicksilver who is rumored to be resurrected but it remains unconfirmed as conveyed by Christianpost.