i agree that the Packers would at least have been a regular playoff participant and maybe more with Super Joe at QB. The 49er teams he played on did not always have a dominating running game, but it did not seem to matter.
As a Packer fan, the one i dwell on even more than passing on Montana is...what if the Packers had drafted Barry Sanders when they had the chance, instead of the mostly useless Tony Mandarich???? And then assume, as in real life, that they went on to add Brett Favre a season or two later.
Would that have been an unstoppable offense, or what???? Load up the box to stop Barry, and Brett will burn you through the air. Concentrate on stopping Brett and the passing game, and he will just hand off to Barry. ANd then, if Sterling Sharpe had stayed healthy, i think the Packers would have had a a running back/quarterback/go to wideout combo at least as good if not better than what Dallas had with Smith/Aikman/Irvin. And then it is the Packers who win multiple Super Bowls in the 1990s, and not the Evil Empire from Dallas.
And then, of course, there is the question of "what if Dan Devine does not trade a whole lot of high draft picks for an over the hill John Hadl..."