The Vikings could guarantee themselves one more year of Darnold at roughly $40 million by using that tag. They could also gauge the market for Darnold, something that figures to happen at least informally during Super Bowl week and later this month at the scouting combine, in order to decide how many teams are interested in signing him and at what price, should he make it to free agency.
From there, the Vikings could use the franchise tag to retain control of Darnold in order to work out a trade, ensuring they receive some compensation for what figures to be a considerable asset. Or they could find the market is cool enough that tagging him is too risky while finding that potentially re-signing him to a team-friendly deal is possible.
From much of the national media at the Super Bowl, a narrative will emerge (and already has) that the Vikings are exploring all options and might, in fact, keep Darnold.
This is consistent with what they have already said and is true primarily because no decision has to be made yet and no team should yield leverage before it is necessary. That is how the Vikings played things last year with Cousins, right up until he unsurprisingly left for Atlanta (as many signs had indicated he would).
But take it all with a grain of salt — or maybe a pinch of it if Darnold decides to show up for some fries at a Shake Shack in New Orleans this week.