It was never a sure thing that the 49ers would make a reunion happen between Cousins and his former Washington coordinator, Kyle Shanahan, next season in free agency. If nothing else, Washington could always have either put the franchise or transition tag on him again … or, in the upset of the decade, agree to a long-term deal.

Of course, if anyone really envisioned the team and Cousins closing their bizarre gulf and agreeing to a contract, the 49ers and Shanahan would never have loomed for 2018. Nevertheless, with the 49ers trading for Jimmy Garoppolo as their quarterback of the future, that question is moot.

IYER: 49ers-Patriots trade a win-win

And that question triggered an avalanche of wisecracks about how soon Cousins would become a Bronco, because of how lousy Trevor Siemian was playing in Kansas City at the time the 49ers trade broke. Most of the jokes were just that. All of them had a germ of truth in them: The Broncos’ situation is as unstable as they come, with 2016 first-round pick Paxton Lynch still returning from a preseason shoulder injury, and their backup Monday night being Brock Osweiler.

If John Elway is not on the market for a quarterback next offseason, he should be — or else the Broncos should be on the market for a new team president.

And the Broncos were one of just half a dozen or so teams that suddenly had reason to think hard Monday about Cousins and what he’s worth. Besides Denver and Washington, they were:

Browns. With the Sashi Brown-Hue Jackson regime at 0-8 this year and 1-23 overall, who knows who will make the decision about a quarterback next year? They appeared to be frontrunners for Garoppolo last offseason, but the Patriots held onto him until Monday. They’ll have a chance at another quarterback at the top of the draft again, but clearly, drafting quarterbacks is not their forte.

Cardinals. The Carson Palmer era is all but done in Arizona. They’re probably good enough to hang around .500, so they won’t be in position to draft someone high. They also have a veteran team, which means Cousins makes more sense than a youngster.

Jets. There’s still time for them to fall on their faces after three straight losses following a 3-2 start. So the tanking talk may not be premature, after all. However, who knows if the quarterbacks expected at the top of the draft a few months ago — Sam Darnold, Josh Rosen and the like — are worth it? Or worth more than Cousins would be, even for what he would command?

Jaguars. This is the last year and the last shot for Blake Bortles, and while he’s been less objectionable lately than he had been, and while his defense and Leonard Fournette clearly are carrying the team, he’s as expendable now as before. A playoff-ready roster run by Tom Coughlin would look more at a Cousins than at a newcomer.

Bills. Having a strong season for an unexpected playoff contender doesn’t make Tyrod Taylor’s future more secure in Buffalo, under a new coach and flaky, impetuous ownership. Why the Bills would back up the truck for Cousins after not wanting to do that for Taylor isn’t clear, but stranger things have happened.

Vikings. Sam Bradford’s chronic injuries interrupted yet another season. Case Keenum isn’t the long-term answer, and Teddy Bridgewater is still weeks away. Who do the Vikings commit to, and for how much? Like the Cardinals, they have pieces in place to compete now.

Those are all varying degrees of possibility for Cousins. It’s all because the biggest possibility, the 49ers, became an impossibility.