Fantastic Films magazine? They did a lot of wild speculating back in the day between sequels. I need to find those and see if anything was on the money. Not sure they were still in business by the time Jedi was out.
They were!
The Internet Archive has their May of 1983 issue, covering ROTJ, here… but they only have the pages covering The Dark Crystal. So we can’t actually read the article titled “Return of the Jedi: The Final Speculation”.
The IA also has an interview with Kurtz, plus some Dark Crystal stuff from February of the same year, and the Dark Crystal coverage from November, 1982. So basically, the articles exist, but IA only has things related to Dark Crystal.