With the Multiverse Saga nearing it's end with Avengers: Doomsday and Secret Wars, the next saga is already close. With Disney's acquisition of Fox and it's rights to Marvel characters like the X-Men, it is likely the next Saga will focus on the mutants. It could be named The Mutant Saga, but if the Phoenix Force comes into play The Phoenix Saga would be an apt title as well. However, the world of the MCU is also still occupied by the Avengers and other superheroes. So, here's a look at what the trilogies, titles and release dates could look like.
Spider-Man: The City That Never Sleeps
The next Spider-Man movie, Spider-Man: Brand New Day (2026), follows Spider-Man as he works with the DODC to incarcerate street level villains. The working relationship turns sour when Spider-Man discovers they have Alistair Smythe keep Rachel Summers against her will. Smythe even manages to unleash the Savage Hulk, but Spider-Man beats him with Punisher's and Rachel's help. Then, Spider-Man: The Next Day (2028) follows Spider-Man fighting Kraven, Agent Venom, Mr. Negative and eventually Knull. Peter also meets Miles Morales, who ends up gaining powers too.
The trilogy comes together in Spider-Man: One Last Day (2030). As Peter teaches Miles his newfound powers, Kingpin returns. He has the Thinkerer equip the Vulture, Scorpion, Mysterio, Shocker, and Hobgoblin (a corrupted Ned Leeds), and forms the Sinister Six to fight the Spider-Men, Daredevil and a defected Black Cat. Outside of this, Spider-Man will most likely appear in Avengers: Secret Wars. That movie could even see him unite with the other live-action Spider-Man in a Spider-Corps, similar to the Thor Corps from the eponymous comics. Moreover, Spider-Man (and She-Hulk) could join and the Future Foundation too.
X-Men: The Mutant Saga
The saga could kick off with Uncanny X-Men (2028). It follows the first team of the comics (Cyclops, Beast, Marvel Girl, Angel and Iceman) as they are revealed to the world by Mr. Sinister. Sinister plans to use Cyclops and Marvel Girl to prepare for a future threat, but is foiled by the X-Men. With mutants now out in the open, the X-Men are attacked and abducted by Sentinels in Giant-Size X-Men (2031). Only Cyclops remains, who recruits Wolverine (introduced in his own tv show), Banshee, Storm, Sunfire, Colussus, Nightcrawler and Thunderbird to defeat the Sentinels and free the abducted mutants.
The threat Sinister has warned off finally arrives in Astonishing X-Men (2034): Apocalypse. Both the Blue and Gold teams work together with the time-travelling Cable to defeat him. However, they learn Jean was a clone replaced by Sinister and the real Jean is in space. X-Factor, a companion tv show, could expand on the school's students like X-23, Shadowcat, Psylocke, Dazzler, Gambit, Jubilee, Bishop, Magik and Rogue and villains like Magneto's Brotherhood and the Hellfire Club and, while Starjammers focuses on threats from space and Excalibur focuses on MI-13's adventures.
Avengers: World's Mightiest Heroes
The next Saga could start with Avengers: Annihilation (2030), where Annihilus is coming for Earth. It's up to Nova, Captain Marvel, Thor, Hercules, Rocket's Guardians of the Galaxy, the Eternals and the Fantastic Four to form a united front against the coming attack. Annihilation could serve as conclusion to the arcs of Captain Marvel, Thor and Rocket. Following this is Avengers: Disassembled (2033), where Magneto teams up with his daughter Wanda against the Avengers. The Avengers eventually triumph over them, but not at the cost of the mutant population being severely reduced.
Finally, the Saga comes to a close with Avengers vs. X-Men Part 1 (2036) and Avengers vs. X-Men Part 2 (2037). When Jean, embued with the Phoenix Force returns to Earth, Cable and the X-Men fight the Avengers to protect her from them and the Shi'Ar. Part 1 ends with Jean succumbing and the Force being split in five parts. It merges with different X-Men, including Cyclops, and in the following year they reform the world. In Part 2, the Avengers and X-Men once again come to blows as the Phoenix Five's power grows unchecked. The conflict ends when Cable's daughter Hope absorbs the Force.
Meanwhile, on the tv side Thor, Captain Marvel and Hulk fend off the Dark Avengers -Norman Osborn, Hercules, Abomination and Zemo- attacking New Asgard in Dark Avengers, while Midnight Sons, Young Avengers and West Coast Avengers form the Mephisto Saga. The teams are taking on Dracula's daughter Lilith, Lilith and Mephisto's son Blackheart, and finally Mephisto himself respectively. Movies that will be released in this saga as well are Doctor Strange in the Dimension of Darkness, Blade, Armor Wars, Black Panther 3, Nova, Shang-Chi 2 & 3 and Fantastic Four 2 & 3.