In an interview to IGN at the D23 Expo, John Lasseter revealed that there won't be a time-jump and The Incredibles 2 will be set right after the first film.
"It starts right as the first one finishes, so it just carries on," Lasseter said during an interview at D23 Expo, quipping that only "a minute" will have passed. He added, "It starts with the Underminer and a big old set piece. You know that at the end of the first movie when he comes up and you see the family dressed as superheroes, well that's where start this movie."
Additionally, Disney released this concept art for the film on the D23 featuring the cast from the first film (minus Syndrome and Mirage) and the underminer seen at the end of the first film. Also there seem to be a raccoon there as well.
The Incredibles 2 will be released on June 15, 2018.
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