OK, let's start with the disclaimer: It seems unlikely that Kirk Cousins plays for the Vikings in 2018 because a lot of things would have to happen to make that a reality.
That said, let's back up a bit and talk about what we do know:
*Cousins and Washington, the team that drafted him in the fourth round in 2012 (the same year they took Robert Griffin III with the second overall pick in the first round), have failed to come to an agreement on a contract extension. It seems quite possible at this point that Cousins will hit the open market in 2018, something that is very rare for a quarterback of his caliber in today's NFL.
*Cousins is coming off of two very good seasons. He threw for a combined 54 touchdowns and 23 INTs in 2015 and 2016, throwing for more than 4,000 yards in each (nearly 5,000 last season) while starting all 16 games both times. His Total QBR ranked sixth in the NFL both seasons, meaning he is inching toward elite status.
*The Vikings have a complicated quarterback situation of their own. Teddy Bridgewater continues to make progress in his injury recovery, but there is no clear timetable still for his return — and no guarantee how effective he will be if and when he does come back. Sam Bradford, acquired in a trade after Bridgewater was injured, is entering the final year of his contract with the Vikings.
All of those factors make it at least plausible the Vikings could be in the market for Cousins. It seems far more likely that either Bradford or Bridgewater will be under center in 2018, particularly since one would imagine the Vikings would have their QB situation figured out long before next offseason, but the possibility for Cousins is at least strong enough that ESPN's Dan Graziano listed Minnesota among his 10 teams that could be suitors for Cousins.
He wrote: Odds are, (Bridgewater or Bradford) will be Minnesota's quarterback in 2018. But health and market factors could mess with the plans and leave the Vikings shopping for QB help. They would come to the table with more than $55 million in cap space.
There would seem to be other teams on that list more desperate for QB help than the Vikings. But …
What if the Vikings have a bounceback year in 2017 during which their defense is dominant but their offense (particularly QB play) is only average? Say they make the playoffs but stall quickly because they can't put up postseason points and enter 2018 thinking they are a QB upgrade away from serious contention?
Hey, stranger things have happened. That exact thing happened, actually, from 2008 to 2009, culminating in an upgrade to Brett Favre.
With the Vikings, never say never. Always say "you never know."