Whatever happened to Willard Huyck and Gloria Katz? As far as I can make out, Radioland Murders was the last film they ever wrote. Did they stop working for some reason? Did they die? Were they both just figments of George Lucas' imagination?

"It'd be like killing the imagination."

Roger Henderson, toward the end of Radioland Murders...

Radioland Murders was meant to be Lucas' next film in 1978...

It didn't get made/released until 1994...

Roger and Penny Henderson are maybe the parents of Dreyfuss' character in American Grafitti, the film that helped set Lucas' career in motion.

Did Lucas want closure? Kill those who'd helped him?

Or is Lucas just a front man for Willard Huyck and Gloria Katz? An actor hired to draw public attention away from them, so that they're not distracted from... something else?

Am I entertaining theories based on nothing more than a few lines of text and a coincidence?

Yup.