I think people here are willing to wait, and let the likely stench of this reboot fade. Plus, that would make F4 a phase 4 film, which is fitting if you ask me. Marvel, though will be quicker in utilizing the other characters like Silver Surfer and Galactus I believe.
Maybe as minor players. I feel like Uatu will come first. Phase 3 is already packed as it is and Guardians 2 will either be about the Eternals or Universal Church of Truth, probably the latter just to involve Adam Warlock and the Soul Gem first. I'd rather the FF join Phase 4 in 2020. This is my ideal Phase 4 if the rights revert.
ABC series for She-Hulk and MS. Marvel which are both rumored
Disney Channel series for Power Pack
ABC Family series for Avengers Academy and Runaways
Netflix series for Black Widow, Moon Knight, Ghost Rider, Punisher, Elektra, Thunderbolts, Blade and Hawkeye all but Moon Knight have been rumored
2019
November - Spider-Man: The Death of Jean DeWolff
2020
March - Doctor Strange: Ascent Into Hell
May - Iron Man: Armor Wars
July - Incredible Hulk: Ghosts of the Past
November - Fantastic Four (Origin story with Annihilus as the antagonist. Cross between 616 and Ultimate origins.)
2021
March- Ant-Man 2 (Whirlwind as villain)
May - Guardians of the Galaxy: Annihilation (Annihilus as villain)
July - Spider-Man: Venom
November - Thor: The Dark Gods
2022
Captain America: Two Americas
May - Inhumans 2
July - Captain Marvel: Live Kree or Die
November - Black Panther :Gorilla Warfare (Shanna the She-Devil co-stars to fight the poaching Man Ape)
2023
March - War Machine: Dragon Seed
May - Mighty Avengers: Atlantis Attacks
July - Spider-Man: Maximum Carnage
November - West Coast Avengers: Kang Dynasty
And yes, this would only be possible if Annihilus and Kang reverted to Marvel. I'd also tease Doctor Doom after the credits of Fantastic Four, Black Panther and Mighty Avengers to set him up for Phase 5. He'd also get a mention in Fantastic Four as the frontrunner for the Nobel Prize in physics after his breakthroughs in AI research which is controversial as he's the ruler of Latveria and he's Reed's competition. After Reed decides to hijack the shuttle after one of his crew gets sick (Doctor Whitman) and puts Johnny in his missing crew member's place, he opens a wormhole to the negative zone and shoots cosmic rays through it just to see how they're affected when they enter and then come back... except Johnny has no idea what he's doing the ruins the mission for everyone. And then Annihilus comes aboard as a stowaway. Think Apollo 13 meets Alien with the shuttle not only damaged but the crew having to cope with newfound powers and fight off an alien invader before they can safely return to Earth while. Ben also finds an extra-large space suit on the shuttle after transforming so he doesn't have to wander around named. The first post-credits scene would involve Annihilus returning to our universe again, except this time he's hovering above Hala and he has reinforcements. The second scene shows Reed accepting his Nobel Prize while Doom looks on angrily from behind a monitor in a lab filled with machines.
Doom would next show up at the end of Black Panther in a post-credits scene where he's shown meeting with T'Challa deep within Doomstadt.
Finally, we see Doom again at the end of Mighty Avengers when Namor is shown as a hero for defeating Attuma and the newest Avenger despite wreaking havoc across the surface world in the 1st Act with Eastern Europe being the site of a massive tsunami. Doom vows to stop the Avengers for daring to allow Namor to join them, no matter the cost.
Oh and Phase 5 is going to be Dark Reign so expect to see storylines like Black Panther: Enemy of the State, Iron Man: World's Most Wanted, Captain Marvel: War of the Marvels, Thor: Gods and Men, Spider-Man: The Night Gwen Stacy Died and Spider-Man: Kraven's Last Hunt. It's a world where Norman Osborn and Victor Von Doom have taken over, the heroes are hunted and Asgard now hovers above Earth. All of which was Kang's backup plan in the case of his death as reality hasn't retruend to normal all culminating in West Cost Avengers: Disassembled and Mighty Avengers: Siege as Doctor Doom drives Scarlet Witch to madness and the Green Goblin decides to take over Asgard.