Why did he revolutionize the horror genre and dominate for twenty years? What would it take for another horror icon to get to that level in modern times?

Sure
>In a rare move, the District Attorney agrees for three co-defendants to be tried in the same trial. Hoffman, Dr. Gordon, and Logan are facing "justice" for their roles as Jigsaw's apprentices and their participation in the activities labeled as crimes by the state. The case has become a massive spectacle among the media and online true-crime podcast types, and the three defendants have been appropriately dubbed "the Jig3". As the court case progresses, we see a series of flashbacks. As a flashback ends, we see that the flashback story was being told by one of the survivors of one of the Jig3's tests. As the trial progresses, tensions escalate at an incredible pace and that has nothing to do with the media and podcasters trying to break down the doors to the court room and ambush key figures in the proceedings at the end of each day. While they initially appear to present a unified front, the Jig3 soon appear to be turning on each other. But there's a lingering sense that nothing in this trial is as it seems, and we soon discover that these court proceedings are connected to the twisted posthumous will and legacy of none other than John Kramer himself.

For all the things that he has done, he never really experimented much or used his Mastermind Archetype powers to dominate the media. Could he easily dominate an interview with a comedian if he paid the right people and used a Rube Goldberg style set up to manipulate the media? Could he orchestrate a shitty reality show? I guess that's the different between actual Mastermind Archetypes and the kind of accidental millionaires flexing their shit muscles we see in The Real World.

Will they be able to take his films to the next level?

As you can See, nobody beats him.

It's his concept.