Fox has announced that both "Dark Phoenix" and "The New Mutants" will be released next year, only adding to the staggering lineup of superhero films due for release in 2019. This is mainly due to the DCEU trying to reboot itself with 3 releases whilst Fox will be releasing most likely their last 2 films before they integrate with Disney. Meanwhile, Marvel has another 3 films and an additional two smaller R-Rated superhero films.
Hellboy (January 11)
Glass (January 18)
Dark Phoenix (February 15)
Captain Marvel (March 8)
Shazam! (April 5)
Avengers 4 (May 3)
Spider-Man: Far From Home (July 5)
The New Mutants (August 2)
Joker (October 4)
Wonder Woman 1984 (November 1)
2016 was deemed the biggest year for superhero movies (Captain America: Civil War, Batman vs Superman: Dawn of Justice, Deadpool, Suicide Squad, Doctor Strange and X-Men: Apocalypse) and then 2017 managed to beat it (Spider-Man: Homecoming, Guardians of the Galaxy Vol. 2, Thor: Ragnarok, Wonder Woman, Justice League and Logan).
Is a saturation of the market about to happen? You know, the same saturation we've been talking about since the decade started. Yeah, not gonna happen next year. but I do think it will eventually, it's just that Disney have found ways to continuously hype up and immaculately market their brands. All good thing do come to an end eventually.