One of the most fun parts of the Arrowverse on The CW was when you’d have all the shows crossing over. But, now that Arrow and Supergirl have ended, Flash is on the way out, and Legends of Tomorrow, Black Lightning, and Batwoman have been canceled, there’s not much of a verse to crossover.
Confirmation of the end of an era comes from Superman & Lois showrunner, Todd Helbing, who had this to say in an interview with Looper.
“We’re a different planet, a different Earth, The Superman that you saw in all the crossovers is not the same as the Superman on our planet. It’s clearly a doppelganger. Part of how this all folds in the big picture with DC is ultimately a DC decision. I’m sure there’ll be more clarity in the future, but as of now, we’re a different Earth in the DC Universe.”
“That version of what we did is probably [done] because we don’t have all of those characters anymore. [From] those shows, all the actors are going to go on and do different projects, or life is going to make them busy. It’s hard to speculate other than they’re still comic book shows. There are guests in comic book shows all the time.”
“I don’t know if we’ll have exactly the same thing – it’s hard to perceive [what could happen in] the superhero genre. It would be great if, four years from now, there was a completely different second wave of this. We could do those. They were a lot of fun, but it’s hard to say.”