Very unlikely that Darnold will take a short term deal. That's the only deal he'll get from Minnesota. Otherwise, if the Vikings shelled out big money for a long-term deal to Darnold, it would completely wipe out JJ McCarthy's rookie contract. Rodgers like every other ex Packer will be inclined to lose with the Vikings. I could easily see him sign a one year deal with Minnesota but even that won't be a bargain. Minnesota has a big decision to make. Sit McCarthy for another year and pay Rodgers big money or roll the dice with McCarthy who is coming off a big injury and hasn't played a down in the NFL. The other option would be to sign Darnold and trade McCarthy, Addison and their 2026 first and second round picks to Cleveland for Myles Garrett.
The trade scenario you describe is interesting. It would definitely take at least a 1st and 2nd round pick to even get to the negotiating table for Garrett, and trading Addison and McCarthy would almost certainly close the deal - at a great cost to the queens. I think Cleveland would jump at that offer.
I don't think even the queens are dumb enough to give up that much for Garrett (ya never know), and then bet the franchise on Darnold. So I don't think it would happen, but it would be an ideal landing spot for Garrett (as would Green Bay).
My guess is that they tag Darnold and let McCarthy learn for one more year. The Vikings have a solid team, much as it pains me to say that, and I don't see them mortgaging the future for Garrett.
While we're talking about Garrett, it will be interesting to see if Gluten makes a real attempt to get him. It would require the kind of draft capital and personnel you mention - a lot. The Packers might have to give up a 1st and two 2nds because they don't have anyone like McCarthy or Addison to offer (unless Willis was thrown in). As much as I'd love to see Garrett in GB, I just don't see Gluten doing it.
It will be an interesting time leading up to the draft, and during the draft.