Originally Posted by AvengingLeague
If it were me it would go like this:
Captain America 3
The Avengers 3
I think this is the most solid and most likely.
In more detail, with some assumptions made.
Captain America (3): Sentinel of Liberty
Red Skull returns, with HYRDA in tow. Turns the state against Captain America, Bucky becomes Cap hunting down Steve-Nomad for the SHIELD, while Taskmaster is hunting him down for HYDRA. Steve becomes the guy to stand for the right even when the whole nation, the whole world community is against him. "No, you move." In the end, Cap and Bucky!Cap take on Red Skull, and the Super Adaptoid to win the day, proving not only that Steve is awesome, but that he can take down someone with all the Avengers' powers combined. Alternately, if Red Skull isn't available, use Viper and add some sexual tension to their adversarial relationship.
Thor 3: Ragnarok
Loki's subplot comes to fruition and the cosmos comes down to Annihilate Asgard with the help of some cosmic foes of various renown. Big Giant Epic LOTR-on-steroids war. Jane Foster dares to speak for gods, Thor maybe dies, maybe comes back to life to start the cycle over again. Play up the Shakesperean tragedy, the familiar betrayals, the tragic lost loves here. Also, drop some Asgardian items on earth to seed future stories.
Crown Prince T'Challa is abroad in school when he learns that the African micronation of Wakanda is in civil war, he returns home to reclaim his throne, but Klaw, his father's killer (cue flashback) is mining the Vibranium for Klaw's sonic weapons and have control of an Idi-Amin-like dictator who's running the country. T'Challa must prove himself, not only to himself, but to his people and the memory of his father to truly become the Black Panther instead of just wear his father's old ceremonial uniform, and then take on the mercs, General M'Baka and the sonic-weapon-prosthesis-wearing Ulysses S. Klaw.
Dr. Stephen Strange is a brilliant famous neurosurgeon, who's hands are damaged in a car accident. He ends up searching the world for a cure and encounters a Mr. Miyagi-like old man in the Himalayas, and ends up stopping a magical murder attempt on the man's life, drawing him into this magic world, where the Ancient One's former student, Baron Mordo, is summoning this Cthulu-like Shuma Gorath creature to destroy the world. A third student, Clea provides additional depth, as Strange learns about the artifacts handed down from the gods like the Eye and Orb of Agamotto. Eventually, Dr. Strange stops wanting a cure, but must face his hand issue in order to properly perform the right gestures. At the loss of the Ancient One, they defeat Shuma Gorath and Baron Mordo, making Dr. Strange the new Sorcerer Supreme
Captain Marvel (just in case)
Pilot Carol Danvers is assigned to investigate fellow SHIELD agent, scientist Walter Lawson whom she discovers is an alien scout. Lawson, bka as Mar-Vell values Carol's humanity and decides to defend humanity, much to his superior, Ronan's shagrin. Ronan unleashes the Sentries 456-459 to take out Carol and other key targets, and Carol discovers that Mar-Vell is on her side when he defends her wit his immense energy abilities due to his Kree Physiology and the nega-bands. They take on the Kree while ducking SHIELD until SHIELD cracks down and captures Mar-Vell, turning him over to the Kree as part of their peace agreement. The Kree prepare to blow things up again but Carol flies in on her jet, saves Mar-Vell from his fight with Ronan, but they get caught in an explosion together which turns her DNA Kree. Mar-Vell dies but gives her his negabands, so now she has his powers. She takes out the remaining Sentries, faces Ronan and proves, both verbally and physically why humanity deserves to live, and deserves their respect. Ronan relents, but appoints her his Kree representative on Earth, the new Captain Marvel.
Thanos returns, having acquired nearly all of the Infinity Gems, and proceeds to come and dismantle Earth. He keeps dismantling it and it's looking like the Avengers aren't coming together. Hulk is corrupted by Thanos, Stark has a Virus, Thor is missing, Cap's been shot, and some of these new guys aren't exactly the team type. Eventually though, the Avengers pull themselves up out of the mire, and come together, Hulk fights off Thanos' influence, Stark reboots himself, Thor returns from the dead, Cap wakes up from his coma and rallies the rest of the team which at that point consists of: Captain America, Bucky!Cap, Falcon, Iron Man, War Machine, Thor, Sif & The Warrior's Three, Hulk, at least one Ant-Man, Black Panther, Dr. Strange, Captain Marvel, Black Widow, Hawkeye, a couple agents from the TV Show (Mockingbird and Quake?), and depending on Avengers 2/Ant-Man's story, Vision. They fall like flies from Thanos' might until one gets through to Thanos, to his gauntlet specifically and breaks it so it roars out of control and implodes him. Any one of them could be that hero. Perhaps multiple endings, perhaps, if the reality/time gem is in effect, multiple realities occur at once to stop him.
Man, I like doin this stuff too much. I would do Planet Hulk with Pixar as a CGI film in continuity with the MCU, lol.