If norwood puts that thru, the Tuna does not exist to the extent that he is portrayed in the annals of the NFL that he does now.
Changing one event in history and assuming that "everything else" plays out the exact same way seems a little flawed to me. Who knows...Maybe Norwood hits that FG, it inspires Parcells, and he ends up winning a half dozen Super Bowls with a completely different team. You just don't know...and neither does anyone else (short of any manipulative time travelers who might be lurking)
It all depends on whether you want to create a positive hypothetical situation with no support or a negative hypothetical situation with no support.
With that said, I'd still like to kick Parcells right in the bean pot for not sticking around long enough to get the job done right.