So it seems your proposal might make bodybuilding less fringe by having the market's desired body type engaging in it, but not affect the decline of pro bodybuilding -- which I thought was the point of your idea. Am I missing anything here?
I have no problem with the demise of contests where judges choose mass over all else. I just want some other type of bodybuilding to replace it. Physique stand and model is not bodybuilding. Who has the best looking muscles while relaxed is not the same as who has the best muscles while flexed. Classic bodybuilding might be a way to get contestants and judges to start paying attention to symmetry and proportionality. And if we have a spectrum of classes, then there's still room for the mass monsters.
Why are athletes choosing to go into Physique classes? One part is they don't want to do the massive amounts of drugs necessary to compete even in amateur bodybuilding, though they're still doing more than most bodybuilders did in the 70s. Another part is they don't like the physiques of the mass monsters, they don't want to be that massive. There should be a way for these guys to compete in bodybuilding.
The underlying problem is the judging. Compare the NPC Nationals and USA to the IFBB European Amateur Championships and World Amateur Championships. The past few years the IFBB Amateurs (claims to be drug free but no one believes it) have far superior physiques, massive but still symmetrical and proportional, V taper. All drugs are available everywhere, so if athletes outside the US are avoiding certain ones, such as hgh and insulin, it's because they know the resulting physiques don't win contests over there.
Physique is not bodybuilding because of the stand and model and the board shorts. But Physique is already outdrawing bodybuilding because the fans can relate to the contestants. Clearly there is a demand for such physiques on stage. But the powers that be are doing it in a way that will kill off bodybuilding. The promotors are going to go where the money is. Endorsement contracts will go where the fans are. As long as they are different sports, the rise of Physique will be the demise of bodybuilding.