Aaron Rodgers is still Aaron Rodgers. The NFL is vastly different from the NBA in terms of playoff windows. For example, Harden was with the Rockets for 8 years. It's arguable that the last 6 of those years was their championship window. With the exception of elite QBs and franchises, most NFL teams do not get a 6 year window.
An example would be the Eagles. After winning the Super Bowl and going 13-3, they've gone 9-7, 9-7, and 4-11.
Same story for the Falcons. After losing in their infamous Super Bowl and going 11-5, they've gone 10-6, 7-9, 7-9, and 4-12.
Rodgers on the 49ers would give us the best chance at winning a Super Bowl. That's the goal every year, no time to rebuild.