I think the film's success has alot of implications not just for DC films and WB, but for the Genre in general.
1) It reaffirms for WB that their strong suit with regards to cbm are the solo and standalone filmmaker driven films like TDK Trilogy, WW, Joker, Superman 1, Aquaman, Batman 89, etc not the universe building overly connected type of films that alot of fans wanted and that WB tried to create.
2) It's helped open the door to a new type of cbm, i.e. the film about the villain. Venom got there first , but now Joker has also demonstrated that there is potentially new ground for DC and Marvel to mine. You can tell stories about the villain and not limit the villain to an antagonist in their foe's film.