For both Pixar and Disney, the question was not if The Incredibles (2004) would have a sequel, but when The Incredibles would have a sequel. Pixar, after all, had already released one sequel, Toy Story 2 (1999) to great acclaim, and The Incredibles seemed the natural choice for the next sequel: a film/franchise with engaging characters and nearly limitless story opportunities. The film had even ended with the Incredibles gearing up to fight their next villain.
Best of all, writer/director Brad Bird was willing to do the sequel. He even had some ideas for it.