When Jon Stewart and Brian Williams happened to disclose the next chapters of their careers nearly simultaneously Tuesday, the confluence of events was greeted with an obvious joke: What if they simply exchanged jobs?

You have a news anchor whose downfall, some have suggested, was fueled in part by his overly keen interest in exploring the world of entertainment. Then there’s the comedian who transcends categorization as mere entertainer with his potent satire of current events.

The vacuums both men leave behind make it only natural to wonder what it might be like if they switched chairs. And while it’s a fairly preposterous notion, one half of the equation is actually worth taking seriously.

While Stewart has never openly aspired to be in the news biz, Williams sure seems to have his eye on Hollywood if his reported interest in being considered to replace Jay Leno on “The Tonight Show” is true. It’s part of a disturbing portrait of Williams that has emerged in the press lately, depicting a man who so enjoyed his flirtations with showbiz via “Saturday Night Live” and “The Tonight Show” that he was essentially seduced into thinking he belonged in that world.

As Stewart himself joked, it’s as if Williams suffered from Infotainment Confusion Syndrome; the man seemed to spend so much time in both the news and entertainment sectors that it scrambled his brains.

Now that he has six months’ worth of free time on his hands courtesy of NBC’s suspension, maybe Williams should actually take some meetings in Hollywood and come to terms with what a good agent — he happens to not have one, of course — would have told him: He is not a natural entertainer.

What Williams doesn’t seem to understand about himself is that the appeal of his appearances on entertainment shows was always subtly rooted in his identity as an anchor. It was about the novelty of watching a creature of one particular habitat adapt to a very different climate for a spell.

The notion that Williams could make the crossover to something like hosting “The Tonight Show” or “The Daily Show” seems like something out of one of those Christopher Guest movies that mines humor from the sadly misplaced ambitions of its characters. Williams may want to get notes from his daughter Allison Williams, who is pretty good playing a delusional romantic on HBO’s “Girls.”

Then again, maybe the contact high he gets from having a star in the family was part of his problem.

Some have held up Williams as a symptom of a problem that has been progressively worsening for years now: the dilution of news by entertainment values in a corporate culture that hasn’t respected clearer boundaries between these two worlds.

There’s a grain of truth there. But what’s bothersome about turning Williams into the poster boy for that troubling trend is that it absolves him of responsibility of his actions to some extent. It’s like he can’t be blamed for exaggerating his stories because the pressures of the corrupted world he inhabited were beyond his control; the infotainment made him do it.

Sorry, Brian, but you’re a big boy who understands the difference between journalistic right and wrong. Just because your career became increasingly fabulous doesn’t excuse being a fabulist.

Then there’s Stewart. There’s been plenty of evidence for many years suggesting meaningful numbers of Americans get their news from entertainment programs like “The Daily Show” or “The Tonight Show” instead of actual news programs. Planting Stewart in the “Nightly News” anchor chair is really just taking that trend to its logical conclusion.

NBC Nightly News With Jon Stewart” might seem a fantastical notion. But it really isn’t when you consider that just a few months ago, the Peacock’s news division approached Stewart’s reps about his interest in taking over for David Gregory on “Meet the Press.” Had he been interested, perhaps Chuck Todd wouldn’t have gotten the job.

Is it really such a leap that NBC could also consider Stewart for “Nightly News” as well? Don’t the network’s evening news and Sunday morning franchises share the same exalted plane of existence?

Obviously, a Stewart-led newscast can’t be anything but an overhaul of the format as we know it, but that’s precisely the point. Given all the hubbub surrounding Williams’ sins, you might think the evening news is this incredibly valuable, sacred ground. But this daypart has been diminishing in importance for decades. All the more reason to take a fresh, even radically new approach to the news that would be truly groundbreaking.

The awful truth is that the evening news as we know it doesn’t matter as much in the digital age. There’s no need to be precious about protecting a format that has been overshadowed by 24-hour cable channels, websites and apps.

Stewart might actually be able to pull off the unthinkable: Grow the 6:30 p.m. audience. Perhaps that might seem too risky given the demographic reality of the evening news as evidenced by an advertiser base populated by the likes of Ensure, Polident and Viagra. But in the rapidly transforming world of TV, that 6:30 p.m. timeslot doesn’t have to limit its audience considering advances in the monetization of time-shifted programming and the ubiquity of YouTube clips.

That doesn’t mean Stewart needs to just reboot his “Daily Show” shtick on NBC. Perhaps this time around, Stewart would approach the news less as a satirist and more as a journalist who just happens to have a wicked sense of humor. He has incredible goodwill with a loyal audience who would likely follow him as he tries just about anything.

No one could blame Stewart for spending the rest of his working life in semi-retirement given the incredible legacy he’s established for himself with “The Daily Show.” But he has the opportunity to cross over into a different business and leave perhaps an even more impactful legacy.

Can the same be said for Williams? Don’t bet on it.