I don't believe the OP's premise that people will change their opinions of Dak if he has a good regular season and play-offs.
I also do not believe, if Dak and the Cowboys were to win the Super Bowl, that any of the hard core Dak-tractors would alter their thinking.
Fact is, if it were down to one minute and eleven seconds with one time out, and Dak drove the team 93 yards and a score to win it all, the prevalent opinion espoused here would be the defense won it and Dak was merely a bus driver, and an incompetent bus driver at that.
People don't routinely change sides during these Hatfield and McCoy fueds.