As for the projects themselves, Reeves (writer/director of The Batman) is highly involved with/producing each one, overseeing the entire universe, hiring many of the writers/showrunners/directors himself, is the creative vision, etc. Here's the current slate...
THE PENGUIN
- A TV series that begins filming early 2023 for a late 2023 release on HBO Max.
- "Expands upon the world filmmaker Matt Reeves created for Warner Bros Pictures' global blockbuster The Batman and centers on the character played by Colin Farrell in the film." - Warner Bros. Press Release
- Will take place in the immediate aftermath of The Batman, in the wake of the death of Carmine Falcone (John Turturro), and will revolve around the Penguin's rise to power in Gotham's criminal underworld.
- Cristin Milioti will play Sofia Falcone, daughter of Carmine Falcone (and half-sister to Selina Kyle/Catwoman), squaring off against the Penguin for control of Gotham.
ARKHAM ASYLUM
- A second HBO Max series that only recently hired a showrunner, so I wouldn't expect this one to be filming until late 2023/early 2024, for a 2024 release.
- "The Arkham Asylum show does not have an official logline at this time, but Reeves previously described it as 'like a horror movie or a haunted house that is Arkham.'" - Variety
THE BATMAN SEQUEL
- Reeves and co-writer Mattson Tomlin are currently writing the sequel.
- Filming likely won't begin until early 2024. And seeing as Warner Bros. is releasing Joker: Folie a Deux (The Joker sequel) on October 4, 2024, and would never release two Batman-related theatrical features in the second half of 2024, we're almost assuredly not going to see The Batman sequel until 2025. My guess would be summer 2025, spring at the earliest, and that it will chronologically follow both the The Penguin and Arkham Asylum series.
- No details are known about the plot.
ADDITIONAL PROJECTS
"[Reeves] is meeting with writers and directors to build out movies - yes movies, not just series - focused on Batman rogue's gallery, both established and more obscure, with characters ranging from the Scarecrow to Clayface to Professor Pyg. All those projects are in the very early stages of gestation. - The Hollywood Reporter