Ever since the release of Deadpool, there has been a greater focus on the potential for R-rated superhero movies, yet, the Marvel Cinematic Universe has remained strictly PG-13. Will that be changing anytime soon? Marvel Studios head Kevin Feige was recently asked the question and while he doesn't discount the possibility that it certainly could happen down the line, there are no plans to bring more adult content from Marvel Studios. According to Feige...
Not currently planning. I don't think it's out of the question. When I started at Marvel 17 years ago, the Blade franchise was doing very well. A lot of people didn't even know that was based on a Marvel character because at the time they sort of hid the fact that it was Marvel. So, not out of the question, but that's not something we're working on right now.
The very first character licensed out by Marvel and the organization that would eventually become Marvel Studios was Blade, so Marvel has been working with R-rated material from the very beginning. However, like Blade, the other R-rated Marvel films, Deadpool and Logan, have all been handled by other studios who had licensed the characters from Marvel. Ever since Marvel started doing this themselves, they've been staying strictly within the confines of PG-13. The level of violence and language is clearly too strong for a PG rating, but it never begins to approach the R-rating either.
While Kevin Feige is clear to not discount the possibility of an R-rated Marvel film in his interview with France's Allocine, his comments that there are no plans means that we certainly won't see one for more than two years. Currently, we know that the MCU is planned through 2019 with Avengers 4, and Spider-Man: Homecoming 2. At some point after that we know we're getting Guardians of the Galaxy 3 and apparently Spider-Man: Homecoming 3. We're going to guess that Marvel has already planned to make more movies than just these, they're simply not ready to announce them yet, but however many Marvel currently has on their slate, anything that is planned as of now isn't looking to go R-rated, meaning that it will be years before we ever see an R-rated film from Marvel, if ever.
In the end, this is probably a good move. While the R-rated superhero movie is what's "cool" right now, the studio isn't going to jump into it simply so they can say they did. If they find a reason to make a movie for adults they will, otherwise they won't worry about it.
Kevin Feige has said that the next phase of the MCU could be something very different from what we're used to, so if changes continue to be made, perhaps an R-rated movie will become a greater possibility. Until then, most moviegoers will likely continue to be happy with the more family friendly action the studio has been providing. The box office would seem to imply so.