Although the film rights for the DC Comics library are held by a singular movie studio, Warner Bros., the same can't be said for Marvel Comics. The rights of various Marvel superheroes are split between three film houses: 20th Century Fox holds the rights to mutants and the X-Men - including characters like Deadpool and Gambit - while Sony is in charge of Spider-Man and a number of connected characters; The Avengers, as well as other Marvel Comics superheroes, remain with Marvel Studios under the Disney umbrella.
However, when Sony and Marvel Studios struck a compromise to share custody of Spider-Man, bringing him into the Marvel Cinematic Universe in Captain America: Civil War, it opened the door to the possibility of other cross-studio deals. Now, Deadpool director Tim Miller and producer Simon Kinberg comment on the possibility of the Merc with a Mouth crossing over with other studios' characters, specifically the fan-favorite Spider-Man.
In an interview with SuperHeroHype promoting the Blu-ray release of Deadpool, the director said he and Kinberg "have been trying to build bridges" between the studios in order to have Peter Parker (Tom Holland) appear alongside Wade Wilson (Ryan Reynolds). Miller also spoke about his love of comic books that included characters from both DC and Marvel libraries.
Kinberg additionally spoke about the duo's relationship with MCU head Kevin Feige and the possibility of a crossover:
"I would love to see it. Both of us are close with [Marvel’s] Kevin [Feige], we respect and love Kevin. If it were even remotely possible, we will find a way ’cause we’d would love to see it. … I just don’t know if it would be possible."
Based on Kinberg's last comment, it seems likely that there aren't any concrete plans at the moment to have Spider-Man appear in Deadpool 2, which is already in the works and reportedly begins filming later this year. Of course, Peter Parker and Wade Wilson crossing paths later on down the line is another option. But, since Marvel Studios and Sony are the only two film studios to have struck a deal at this point, 20th Century Fox would need to strike their own agreement in order to have Spider-Man appear in a Deadpool film.
That being said, a crossover between Fox's Deadpool and Sony's new Spider-Man - who will appear in a standalone film produced by the studio titled Spider-Man: Homecoming - likely depends on how successful the deal between Sony and Marvel Studios turns out to be. As Marvel Studios proved when they brought Spider-Man into the MCU, they're willing to alter plans to accommodate a character as beloved as Peter Parker. So, if the deal between Marvel and Sony results in critical and financial success, it may open the door even wider to share characters across studios - and perhaps lead to a team-up of Deadpool and Spider-Man.
Deadpool will be released on Blu-ray on May 10, 2016. X-Men: Apocalypse opens in theaters May 27th, 2016, followed by Wolverine 3 on March 3rd, 2017, and unannounced X-Men films on October 6th, 2017 (possibly Gambit), January 12th, 2018 (possibly Deadpool 2), and July 13th, 2018. The New Mutants is also in development.
Captain America: Civil War will release on May 6, 2016, followed by Doctor Strange – November 4, 2016; Guardians of the Galaxy Vol. 2 – May 5, 2017; Spider-Man: Homecoming – July 7, 2017; Thor: Ragnarok – November 3, 2017; Black Panther – February 16, 2018; The Avengers: Infinity War Part 1 – May 4, 2018; Ant-Man and the Wasp – July 6, 2018; Captain Marvel – March 8, 2019; The Avengers: Infinity War Part 2 – May 3, 2019; Inhumans – July 12, 2019; and as-yet untitled Marvel movies on May 1, July 10 and November 6, 2020.