didn't get Joe Johnson get the same salary then LeBron James? if you have an Hardcap on salary, there won't be clones and it wouldn't make sense if it at the current salary of the best player.(marbury would be an great example too)
But yes, it would have a weird development of value, first it go up when the player get better maybe around 200k the value will decrease with training and when the player comes close to the cap(most likely betwen 300-400k) it will start to increase again.