Speaking with Movies.com, Bird says that, while he's open to the idea of a followup, he doesn't want to do a sequel for the sake of itself.
“I want to do it because I have something that will be as good or better than the original,” he says. “'Toy Story 2' was, to me, a perfect sequel, because it absolutely respected the first film but found new places to go without selling out its characters. So if I could come up with an idea that is to 'The Incredibles' what 'Toy Story 2' is to 'Toy Story', I would do it in a second.”
Though some time has passed since the first film, Bird admits that he hasn't been actively concentrating on coming up with a plot for a sequel and, though he does have a few good ideas, there's nothing to tie them together yet.
“I would like to think that I have several good ideas that could be incorporated into a next 'Incredibles'," he says, "but I don’t have a whole movie yet, and the last thing I want to do is do it just because it would open big, or something like that.”
You can read the full interview over at Movies.com.