This is my plan for a reboot of the DCEU. Imagine all work on current DCEU movies were halted, and a new cinematic universe begins starting in 2020:
Batman (2020):
I think Batman is the guy to start with. It's been ages since he's actually had a solo film and he is perhaps DC's most popular character. You start the universe off with this crime-ridden, hope-forsaken picture of the world, where an older Batman is still struggling to do some good, and that then sets things up for Superman to arrive and bring hope to the world. For the villain, I'd go with Hugo Strange, as a doctor who experiments on his patients at Arkham Asylum. The Asylum is the perfect place to establish that Batman is an established crime-fighter with many of his enemies already locked up. Specifically the Joker. Have the Joker in the background taunting Batman throughout. Establish the death of Jason Todd as an event in Batman's backstory.
Catwoman (2021):
Probably not a lot of people's first choice for a phase 1 DCEU movie, but she's one of DC's best known and most popular characters. With the current Justice League cast somewhat tarnished, you've got to go with a bold, new lineup. She also helps set up a potential Gothamverse: a cinematic universe within a cinematic universe, if you will, eventually featuring a large range of properties (Batman, Catwoman, Batwoman, Birds of Prey, Gotham City Sirens, Suicide Squad). For the film itself, I'm envisioning a hedonistic romp, wherein Catwoman pulls off a heist against The Penguin. A fun blockbuster on the surface, disguising Selena's trauma.
Superman (2021):
What Man of Steel got wrong, was that Superman was just as dark and brooding as the world around him. You can have a dark setting for a Superman film, but he's got to be the light in the darkness. The Superman films need to do what the Captain America films have done in the MCU, but on an even grander scale. In these trying times, a character who is truly kind, optimistic and selfless can be interesting, especially if you give him a bit of a sense of humour. For the villain, let's not beat around the bush - straight into a proper Lex Luthor.
Wonder Woman (2022):
Seems a shame to do away with the DCEU's one real hit, but there we are. It's easy enough to distinguish a reboot from Gadot's Wonder Woman by having it set in the modern day. Circe as the villain.
Batman Sequel (2022):
Just as The MCU followed Iron Man up promptly with its sequel, so too should the DCEU do the same for Batman. It establishes that this is a series of franchises, not one-and-dones to set up Justice League. Now that Superman has landed, the superpowered individuals of the universe have begun to come out of the woodwork. So I'd pit Batman against a more out-there foe, like Clayface. Catwoman would feature heavily, cashing in on some of that cross-over hype before Justice League.
Hawkwoman (2023): Captain Marvel is set to skip over the original male character in favour of a bit more female presence. Hawkwoman would do the same. Any writers here have a bit of a challenge streamlining the convoluted mythology of Hawkman and Hawkwoman into one. My take on it:
Shiera Sanders is an archaeologist excavating in Egypt. She stumbles upon Katar Hol's Mace and Wings, and the Claw of Horus, thinking they are Egyptian artefacts. In reality, they are alien weaponry and the Claw of Horus contains the "soul" (aka digital mind upload) of deceased Thanagarian police officer Katar Hol. When she touches the Claw, her mind merges with Katar and she essentially becomes his reincarnation, occasionally hearing his voice in her head guiding her. The villain would be Byth Rok, a fugitive from the Thanagarian police force who has stolen an experimental drug that gives him shapeshifting powers.
Martian Manhunter (2023):
The final solo movie before Justice League. We start the film with J'onn already living in hiding as detective John Jones on Earth. With Superman revealing himself to the world, J'onn eventually decides that is time to stop living in hiding. The main villain would be Despero, an alien genius bruiser with both super strength and psionic abilities. The backstory would tell us of the destruction of Martian civilisation, hinting at the villain for Justice League.
Justice League (2024):
After 4 years of build-up, Batman, Superman, Wonderwoman, Hawkwoman, Martian Manhunter and yes, Catwoman team up against Braniac. Braniac will be the villain behind the destruction of Krypton and the Martian Empire, and now his sights are set on Earth.
Catwoman may seem a strange choice for a member of the Justice League, so I feel like I should justify that: With Flash, Aquaman and Cyborg probably in need of a rest to differentiate the reboot from the first attempt, you have to go in a different direction. Catwoman is a popular character (I think we're past the damage the 2004 movie did) and her inclusion early on alongside Batman means you can start getting natural character crossovers in a lot sooner. I could see her being reluctantly roped into hero work, say if she comes across an alien artefact on a heist which kicks off the plot, and her skills of infiltration could make her useful even amongst characters like Superman and Manhunter. I'm picturing a very young Catwoman, who is already disillusioned and turned to crime. Her cynicism at such a young age would demonstrate the kind of world that this is, how much it needs Superman and the League to bring it hope.