Information from the wikis on how far in the future Batman Beyond is supposed to be, as compared to DCAU's set-in-the-'present' Batman properties, goes:
Though it is not directly stated, Bruce Wayne's final fight takes place thirty years after Batman: The Animated Series, twenty years after The New Batman Adventures, and ten years after Justice League. [1]
and again
The pilot episode, titled "Rebirth," initially begins in the year 2019, 20 years after The New Batman Adventures. ... The story fast-forwards to 2039 in Neo-Gotham, a futuristic megalopolis featuring staggering high rises and flying vehicles. [2]
What is the source of this information?