With Marvel Phase 3's final film being the Inhumans, the fourth phase of the Marvel Cinematic Universe is set to start in May 2020 Now for these three unrevealed mystery films they are certain to be sequels to previous stand alone films, some maybe as spin offs and some as the start of another addition to the cinematic universe for the first and second unrevealed films, it is quite possible that they are Iron Man 4 and the second MCU Spider-Man film
because with Marvel Studios promising to bring out the real and proper MCU Mandarin after seeing his operatives in the One Shot set after Iron Man 3 and from the Ant Man as one of Darren Cross' buyers, RDJ needs to reprise his role as Iron Man once more so that he can take on his character's true arch enemy and not only is Marvel Studios gonna need to lower his salary, but they are also gonna need to replace Shane Black with a director is willing to get the real Mandarin done right without pulling any strings and causing setbacks like Black did in Iron Man 3 and make sure the new director has someone fit for portraying the proper MCU version of the character in the fourth Iron Man film
and while Korean actor Byung Hun Lee is still the best candidate on being cast as the Mandarin, others like BD Wong, Jet Li, and Hiroyuki Sanada are also fine choices for Marvel to choose from on playing the actual Mandarin of the Ten Rings himself. Of course when they choose Lee or any of the other actors that I just mentioned, they won't need to make him a Chinese dictator in a wardrobe but they will need to try having an male Asian American actor portraying the real Mandarin and make sure the role of the villain is handled with plenty of caution and with a lot of care because other than how that turned out in Iron Man 3 with Ben Kingsley ending up a joke over Marvel's lack of handling arab sterotypes as well as having put the wrong kind of people in charge, we wouldn't want them pulling off anymore irritating theatrics like before or end up making the real leader of the ten rings end up looking like a complete wasteful disappointmen than the two knockoffs from the third installment so the real Mandarin would have to blend in with the more civilized world of the franchise and have a much more decent personality than Trevor Slattery but not too much like Aldrich Killian. And while it is unclear if he will still be a part of the government and perhaps the World Council, the real Mandarin is sure to have Ten Magic Rings in his possession and while battling against Iron Man with those rings and meets up with his followers for certain meetings and gatherings he will also wear magic enhanced black battle armor like he did in Iron Man Armored Adventures and the Marvel Disk Wars anime series so that his depiction as the ring blasting arch nemisis of Iron Man in the Marvel Cinematic Universe will turn out more outstanding than in the comics and once Iron Man meets the real Mandarin at last for the first time in the MCU, the real Mandarin himself will explain to Tony on why Killian aka Firebrand from Iron Man 3 would dare frame him and his organization for A.I.M.'s failed experiments regarding the extremis virus as well as why he would dare act like a maniac on intending to kill his own president for control over the world and proclaim himself as who we all know now that he is NOT! And while the real Mandarin is sure to reveal his origin and cause to Tony, it is very much likely to regard immigration from Asia into South America during America's war against drugs during the 80's and the ruins from either country of the continent would be where the Mandarin gets the ten magic rings from and he would have made allies with some of the residents in the South and for how he got people from other countries to join and serve him in his organization is sure to be revealed. And once Iron Man and the real Mandarin have had their major fight in the film's climax, they will be sure to cross again in more films after Iron Man 4 like phase 4's avengers film where the real Mandarin himself would return assembling a team of foes fought by the Avengers in other Marvel phase 4 films that are yet to be announced and after his defeat by Iron Man again he would return as an anti hero helping Iron Man fight against Fin Fang Foom and the Makulan Dragons in a future Iron Man 5 or 6 film or perhaps the 5th or the final Avengers film in phase 6 which is a long way from Avengers 4 after all most of us who will be waiting for the next 5 to 6 years for Iron Man 4 will be desperate on seeing the real and proper MCU Mandarin appear and see him as the real leader of the ten rings take on Iron Man with Ten Magic rings in the cinematic films for the first time. Plus the film, the Mandarin and his plot could also use some Call of Duty Modern Warfare and Black Ops 2 treatment so that doing the proper version of the character can be done in the film much easier and will featuring the actual Mandarin as the main villain for Iron Man 4, Marvel should also feature another Iron Man villain to act as his top apprentice, spy, assassin and second in command of the Ten Rings organization like the Ghost, have Pepper Potts don her Rescue armor so that she can help Iron Man and defend herself against any hostiles and have Harley return to create a new armor for Tony to wear that will allow him to fight and move faster
Now for the other 2 unidentified films one of them is sure to be the sequel to the MCU's Spider-Man reboot.
Now for the second Spider-Man film, Marvel Studios should include 6 of Spider-Man's enemies in the sequel as the Sinister Six (just incase the 2017 reboot doesn't) and have Spider-Man wear the black alien costume and team up with Black Cat and any other local Avengers to take the villains down who should be
Hobgoblin (Rodrick Kingsley)
Rhino (Alex O'Hern in rock solid rhino costume version)
Scorpion (Mac Gargan)
Doc Ock
Shocker
and Vulture (Adrien Toomes)
Afterall we are not sure how much longer Marvel's contract with Sony Pictures will last so just to make sure that Spider-Man's apperance in the Maevel Cinematic Universe is worth it, they should make sure that the sequel gives us plenty of villains to have him take on as well as having other heroes in the franchise show up in the films with, otherwise Marvel's contract with Sony along with Tom Holland's multi picture contract as Spider-Man are gonna need to be extended
and last of all on third mystery movie that has been lined up for Phase 4 could either be the long awaited Incredible Hulk sequel or the possible Black Widow spinoff which is currently on hold with production
and of course there is slight chance that the third phase 4 mystery movie could be Black Panther 2, Thor 4, the potential and yet to be confirmed Scarlet Witch stand alone, GOTG Vol. 3, Inhumans 2, Ms. Marvel 2, or Dr. Strange 2. But a 4th Captain America film, not certain since Captain America Civil War is confirmed to be the end of the trilogy that started from Captain America the First Avenger but we'll see For now continue your speculations on what the three mystery movies will turn out to be and in the meantime before Marvel does any reshoots on Captain America Civil War, tell them to make sure that they will have Elizabeth Olsen's Scarlet Witch make it through the whole movie alive so that we can see more of the character in future MCU films and make sure that Marvel Studios includes Scorpion as a major villain for the upcoming Spider-Man 2017 film for the wall crawler to take on so that their intentions of using Kraven and overloading the film with too much humor and stupidity does not make the film suck.