Washington Redskins quarterback Kirk Cousins will likely have many suitors if he hits the open market next offseason. (Jonathan Newton / The Washington Post)

The first rule of NFL roster construction is simple: If you don’t have a franchise quarterback, you have to do whatever it takes to get one.

The rest of that equation is so self-evident that it rarely comes up: If you do find yourself with a highly productive passer, by all means keep him.

The Washington Redskins have put themselves in jeopardy of violating that generally unspoken part of the rule and, if indeed that happens, some other NFL team will be the beneficiary. Determining which team that will be could be a major story line around the league next spring.

Monday’s leaguewide deadline for teams to sign their franchise-tagged players to long-term deals came and went without the Redskins striking a multiyear agreement with quarterback Kirk Cousins. That means that Cousins will play the 2017 season under his one-year franchise-player deal that pays him $23.94 million.

What happens after that has become anyone’s guess.

It remains possible that Cousins could stay with the Redskins beyond the upcoming season. The Redskins could re-sign him after the season. They could use their franchise-player tag (again) or their transition-player tag to retain him. But possible and likely are two very different things.

It would cost the Redskins a one-year deal worth $34.47 million next season to tag Cousins for a third straight time, an amount that might be cost-prohibitive even for a player at the sport’s most important position. The transition tag would be less costly, at $28.73 million for a one-year deal. It would enable the Redskins to retain Cousins by matching any offer sheet that he might sign with another team in free agency. But, unlike with the franchise tag, it would not give the Redskins the right to receive two first-round draft picks as compensation from his new team if they were to allow him to depart.

There has been speculation that Cousins would be receptive to the possibility of re-signing with the Redskins following the 2017 season. That, of course, is a signal that Cousins and his representatives logically would send: Why eliminate any potential bidder? But, realistically, why would Cousins strike a deal with the Redskins before free agency next spring when he would be so close to being available on the open market? And, based on what has happened over the past couple of years of negotiations, what reason is there to believe that Cousins and the Redskins can strike a deal next spring with him on the cusp of free agency?

It is entirely possible that the Redskins’ last, best chance to keep Cousins over the long term came and went some time ago, before the team’s use of multiple franchise tags made the numbers so big and so potentially unwieldy against the salary cap.

Cousins and his representatives have been unafraid of allowing Cousins to play under the franchise tag. It has paid off handsomely for him.

“They’re teaching other people a lesson,” one agent not connected to the Cousins negotiations said recently. “You don’t necessarily have to go out of your way to avoid the tag.”

Former NFL executive Michael Lombardi wrote on Twitter: “Why would Cousins ever want a long term deal? [H]e is like a landlord that is making so much money renting, he never has to sell[.]”

Cousins turns 29 next month. He is coming off consecutive 4,000-yard passing seasons for the Redskins, having thrown for 4,917 yards last season after amassing 4,166 yards in 2015, his first full season as a starter.

There will be no shortage of teams bidding for Cousins next season if he becomes available. Speculation so far has focused on the San Francisco 49ers, who have former Redskins offensive coordinator Kyle Shanahan as their first-year head coach. And indeed, the 49ers would likely be the top contender. Shanahan and his father, former Redskins coach Mike Shanahan, drafted Cousins and were believers in him from the outset of his NFL career. The Niners need a quarterback and Shanahan’s system would create a situation for Cousins in which he seemingly could thrive.

But the 49ers probably would be far from alone in chasing Cousins. Another former Redskins offensive coordinator, Sean McVay, is the first-year head coach for the Los Angeles Rams. Perhaps they already have a franchise quarterback in second-year pro Jared Goff, the top overall selection in last year’s NFL draft. Perhaps they don’t, following Goff’s difficult rookie campaign.

Teams such as the New York Jets and Cleveland Browns remain in desperate quarterback need, at least for now. A team like the Arizona Cardinals has an aging quarterback, in Carson Palmer, and might be ready by next offseason to look for a replacement. Will the Jacksonville Jaguars be ready to move on from Blake Bortles? Will the Denver Broncos be in the quarterback market if they can’t make things work with Trevor Siemian or Paxton Lynch? Will the New Orleans Saints be ready to move on from Drew Brees?

It would be difficult to envision Cousins leaving his comfort zone to sign with a team whose coach is not familiar to him when, say, playing for Shanahan in San Francisco might be an option. But it certainly would behoove Cousins to encourage as many bidders as possible, if and when the time comes.

Next year’s NFL draft is expected to be overflowing with coveted quarterback prospects such as USC’s Sam Darnold, UCLA’s Josh Rosen and Wyoming’s Josh Allen. The Jets, following their roster purge this offseason, have been accused by some observers of tanking the 2017 season in hopes of being in position to draft one of them. That clearly could affect the market for Cousins. So, too, could the potential availability of New England Patriots backup Jimmy Garoppolo. But there are plenty of quarterback-needy teams and not enough good quarterbacks to go around. There will be a robust market for Cousins.

There are risks to Cousins without a long-term deal. He could get hurt this season. He could have a relatively unproductive season. The Redskins, after all, said their offseason goodbyes to wide receivers DeSean Jackson and Pierre Garcon.

But those risks are mitigated. The quarterback market is such that even if Cousins is coming off an injury or a disappointing season, the bidding for him would be likely to be spirited. The Houston Texans handed a $16 million-per-season deal before last season to Brock Osweiler. Cautionary tale, you say? Think again. The Chicago Bears gave a $15 million-a-year contract this offseason to Tampa Bay Buccaneers backup Mike Glennon.

Even if the Redskins use the franchise tag on Cousins next year and then try to trade him, Cousins would retain some control over his destination. It’s unlikely that any team would trade for Cousins without being able to agree to a long-term contract with him.

Cousins has negotiated his way — or not negotiated his way — into a very favorable position.

It’s good to be Kirk Cousins today.