There will only be two new films in the Marvel Cinematic Universe hitting theaters in 2020, and here's why. Once Disney acquired Marvel Studios and both companies saw the success of a shared universe blossom with The Avengers, the output of these films increased. Starting in 2014, Marvel Studios has released at least two films every year, with 2017 marking the start of a three year run with three MCU films in theaters. This is once again the case in 2019, where Captain Marvel and Avengers: Endgame have already been released, with Spider-Man: Far From Home on the way.
One quick look at the critical and financial success of the last several years of the MCU make it clear that this plan is working incredibly well for everyone involved. There is almost never a time when a Marvel movie is not in theaters or in the thick of a marketing campaign, and this schedule has also made it so it's rare to have a time (like right now) where no MCU film is filming. This minor lull after the Infinity Saga will result in Marvel Studios releasing just two films in 2020 - one in May and one in November - but that wasn't always the plan.
Thanks to Disney and Marvel's longterm plans, they previously announced that three unannounced Marvel movies would hit theaters in 2020. In addition to the May and November releases that are still planned and likely now for Black Widow and The Eternals respectively, they made the decision last year to remove a late July release date. This was a major change to make and came at a point in time when the MCU's future was being shaken up on a number of levels.
One of the biggest changes that came that had a clear impact on Marvel's 2020 plans was the firing of James Gunn on Guardians of the Galaxy Vol. 3. The trilogy capper was slated to begin production at the beginning of this year and Gunn indicated that it would be the studio's May 2020 slot. The script was written and pre-production just a few months away from truly kicking off at the time Gunn was let go, and that decision brought the development of the movie to a halt. Marvel may have kicked the tires on seeing if Doctor Strange 2 or another property would be ready to go in time to fill one of the 2020 dates, but that didn't happen, which left them to remove one of the dates altogether and reshuffle the timelines on Black Widow and The Eternals to make it work.
While the Guardians of the Galaxy Vol. 3 drama is the most likely reason for the lack of a third MCU film in 2020, the sudden influx of Disney+ properties may also be somewhat responsible. Marvel Studios has shown the ability to make it through production on a film with ease, but they've never done TV before in this manner. They have several shows in development and a few that should be filming and releasing this year and next, so alleviating the workload of a third film may have also played a part in making sure they successfully launch this new content stream.
The final reason why only two MCU movies are coming in 2020 could be the result of Disney's acquisition of Fox, which gives Marvel Studios access to the X-Men and Fantastic Four for the first time. Marvel Studios head Kevin Feige has indicated that the deal isn't dramatically changing their plans for the next five years, but slightly slowing down their output could allow for more projects to help introduce these characters. Perhaps unintentionally, Disney will be releasing a third Marvel movie in 2020 though, now that The New Mutants was delayed again.
Two MCU movies may make for a slightly smaller and riskier slate in 2020, but Marvel Studios will quickly return to their (at least) three films a year output in 2021 and 2022. Until then, they'll just need to hope that Black Widow, The Eternals, and Disney+ content will be enough to maintain the popularity that the MCU has had for the last few years.