Samuel Jackson recently talked about this, stating that he’s been waiting for a call about his role on “The Incredibles 2”, and he’s hopeful that he’ll get a chance to reprise his original part. Still, the actor doesn’t seem to have been contacted yet, so we don’t know if he’ll be taking part in the new film.
It’s also possible that he did get contacted but is keeping quiet, and of course we wouldn’t expect him to say anything if he’s under an NDA. On the other hand, he probably wouldn’t be making such specific comments about the upcoming film if he already knew about his role, so we don’t know what the situation is like on that front.
“The Incredibles 2” has a lot of hype surrounding its production, and as soon as the first round of official information has been released, it will be all over the news. With that in mind, the directors of the film should probably focus on polishing the actual production instead of putting any effort in marketing for now.