If Kwan had trained under CoP from the start, she probably could have done a 3Flip-3Toe.
I don't think CoP has anything to do with doing harder triple-triple combinations.
If she had believed that that combination was necessary to win against her competition, under any judging system, and had therefore trained it, she probably could have done it.
To summarize my thoughts on the thread topic,
If Kwan and Kim were approximately the same age and had trained under the same expectations and skated at their peaks at the same time, I believe they would have been competitive with each other and would each win against each other sometimes.
Then throw all the skaters either of them ever lost to more than once into the mix, and you'd have a very competitive field.