I personally hope that, like the MCU, The Incredibles should be a film series but to not have them to long, maybe we can expect short films that would always end in a cliffhanger, until we get Incredibles 3.
My top 5 ideas for Incredibles 3 so far, are (1) the return of The Underminer and Bomb Voyage so the Parrs can capture them this time, but it won't be the main plot, it's just a key part of the story. (2) A little time jump to be occured, but not let Violet, Dash or Jack-Jack grow up. (3) Villains from the glory days returning and even Xerek, but they won't be the main bad guys for a third. (4) The next adventure should about on all of the Incredibles at the same time. They could also travel all over the world fighting bad guys and they should form a new superhero team with Voyd and the Wannabe Supers. (5) The main villain for the third should be the most formidable foe the Supers had ever faced in their whole lives. A villain who is a real supervillain with real powers who is also a mad doctor and he should be based on Thanos and The Joker
I don't know. If Violet is not the protagonist in Incredibles 3 for a future? They do not work like this in Forum as they were failure.