Gotham City is a "dead city" in the modern DC-CW Universe according to producer Marc Guggenheim, and Batman has been missing for years. In an Entertainment Weekly interview promoting the upcoming "Elseworlds" crossover between The Flash, Arrow, and Supergirl - which will make its way to Gotham and introduce Batwoman -, Guggenheim and others involved with the show explain what happened.
“Our approach is: What does Gotham look like after the Batman has been gone for three years? So if you have the law and order, protector, and hope gone, what happens as a result?” said consultant (and showrunner of the potential Batwoman spin-off) Caroline Dries. “Some people are thriving in his absence because now they can start to do their own thing without the oversight. A lot of other people are suffering and they’re losing hope, and the city itself and infrastructure is falling apart. So it’s not a happy place. Our guys walk into a grimy, scary Gotham.”
“It’s a dead city,” Guggenheim added. “The way I sort of described it to [Stephen Amell] is, it’s there but for the grace of God goes Star City. It’s the worst case scenario. The reason no one talks about Gotham is the city might as well be dead. It’s practically a ghost town.”
Grant Gustin states that his Flash argues with Amell's Green Arrow and Melissa Benoist's Supergirl on if Batman is even a real person.
“Oliver is like, ‘He’s not real! They’ve made him up! It’s a hoax just to scare the citizens.’" said Gustin. "Barry is flabbergasted by that and all he wants to do in Gotham is meet Batman. It’s a pretty funny scene."
“Oliver is not enthused about the idea that there might be some other vigilante out there," Amell added.
The three-night event "Elseworlds" crossover event is scheduled to begin December 9 with The Flash, followed by Arrow on December 10, and Supergirl on December 11.