Sports Illustrated, like daily newspapers, was going to die anyway. Replacing all the editors with chicks that don't care about sports accelerated the speed of the death, but the reason for the magazine ceased to exist several years ago.
There were three things that made Sports Illustrated popular: great photographs, the swimsuit issue, and some talented writers.
While I wasn't a huge fan of Peter King, George Plimpton, or Paul Zimmerman, they each had a style. You didn't need to read the byline to recognize their writing. Plimpton could make a story out of nothing, like when he worked out with the Detroit Lions, ran three plays in a preseason game, and got multiple stories and a book out of it(Paper Lion.) In an era where everyone with a webcam has their own sports channel, nobody's going to stand out that much. It's like nobody will ever be another Johnny Carson, cause if Carson was still around, he wouldn't be Johnny Carson, dominating the airwaves. He lived in an era where there were three channels, and maybe one other late night host at a time.
I think it was close to ten years ago that SI fired all their photographers and started using freelancers. After that, their photos started looking just like everyone else's photos.
Going to the trannies and fatties in the swimsuit issue alienated their core audience. Looking back on the last forty years, it's crazy how many models became famous from being on the cover of that issue. Christie Brinkley, Cheryl Tiegs, Elle McPherson, Kathy Ireland. Even leaving out the fatties and trannies, in 2022, Kim Kardashian was a swimsuit model. Guys who spend their lives avoiding seeing Kim Kardashian don't want to open up the swimsuit issue and see her botoxed plastic surgery face and fake boobs.
The biggest thing, though, is that up until the internet, there was a limited supply of information and illustration about specific teams and sports. Like what happened to sportscenter, nobody has to wait to see highlights anymore, and they don't have to wait a week to see photos of big sporting events.
IF they had people who cared about sports running it, they may have been able to hang around by doing commemorative editions for NFL, NBA, and college championships, the swimsuit issue, etc. Hell, they could probably sell 100,000 copies of a Michigan football issue, cause every Wolverine fan would keep that forever. I still have my 2005 Longhorn issue.