Yes! Marvel Studios has announced that Deadpool 3 will have an R rating and will still be a part of the Marvel universe. The concern is that no Marvel movie has ever been rated R, so the question was asked if it could still be considered a Marvel movie.  According to the president of Marvel Studios, the answer is “yes” that it has a home in the MCU and that Ryan Reynolds is looking over the script right now. The other concern is the age limit on Disney+, but that appears to be solved by the upcoming Disney Star service that allows higher age ratings.