*Bradford is going to miss no more games: Zimmer goes home tonight, looks into that crystal ball, and it tells him Bradford is going to play Sunday against Tampa Bay and that the knee will be just fine the rest of the season. The Vikings obviously do nothing at this point, and we go back to imagining a best-case scenario season instead of focusing on the worst-case.
*Bradford will miss one more game: Even then, the Vikings would do nothing. Case Keenum might be good enough to squeeze out a home win over Tampa Bay, and even if he isn't the Vikings' season would hardly be over if they started 1-2 as long as a healthy Bradford was returning.
*Two or three games: This is a good crystal ball, but it's not perfect. Once we get to a certain point, it can only tell Zimmer a general framework of when Bradford will return. And if it's two or three games, things start to get complicated. After Tampa Bay, the Vikings are home against Detroit and then at Chicago. All three are winnable games — but all three are certainly games they could lose, too. If Zimmer knew right now Bradford would be out two or three games, the plan would probably be still to stick with Keenum to hold down the fort, but Zimmer might at least lobby to bring in a more experienced backup than Kyle Sloter.
*Four or five games: Now it gets really complicated. The Vikings have two more home games after that trip to Chicago — against Green Bay and the Ravens. You could roll the dice that a good defense should be enough to tread water if Bradford misses that much time, but you could be giving away winnable games if you stick with the status quo. Still, the guess is that the Vikings wouldn't do anything huge at QB if they could count on Bradford returning after four or five games.
*Six to nine games: Now we're in panic mode, but the Vikings are also entering strange territory because this would be about midseason. And by midseason, Teddy Bridgewater might — at least according to reports — be ready to play. But would you gamble on Bridgewater being able to return as an effective player, at least until Bradford was healthy — and gamble in the mean time that the season didn't fall apart? Or would you try to make a bold move right now if you knew Bradford would miss that much time? Given what we know about the Vikings and their seeming attitude that they need to win now, maybe they would explore an external candidate with the potential to be a starter if Bradford was out that long. The most logical name (by far) in that equation: Colin Kaepernick.
*10 games or more: Paging Mr. Kaepernick? Send a plane to go get Brett Favre? Put your faith in Sloter? Believe in Bridgewater?