The Hollywood Reporter website publish an article about Hollywood's top 100 attorneys, and the best part is that it includes links to important deals they've helped make. The piece notes that one of Warren Dern's attorney clients is Todd Phillips, who "made a deal to co-write the next Joker movie."
Earlier this May, THR also reported that "The Joker" had a sequel planned. However, Warner Bros. Studios has not yet confirmed development. It should also be remembered that back in late 2019, the same publication reported that work on a sequel had begun, which was later denied.
A solo movie about Batman's main enemy was released in 2019, starring Joaquin Phoenix. Todd Phillips directed the picture and co-wrote the script with Scott Silver. "Joker" grossed over $1 billion worldwide and received 11 Oscar nominations.
Production will obviously start not very soon, as Joaquin Phoenix is busy preparing for the role of Napoleon in the Ridley Scott film, but there is reason to believe that the Joker-Phoenix and Batman-Pattinson will still clash in this film.