Will another team ever go undefeated like the 1972 Dolphins? Why or why not?

In todays game i think its hard. Mainly because if you're a 15-0 team and you have no reason to play the last 2 games of the year the you are going to rest your starters to avoid injury, making it very difficult to go 16-0. It would be crazy to see a 14-1 team and a 15-0 team in the same division play each other on the last day of the season, forcing the 15-0 team to play their starters.