"I would have loved Kander & Ebb to have written La Cage aux Folles."
"But would that have won the Tony Award over Sunday in the Park With George?"
I expect so- and would have had a shot at the Pulitzer and Drama Desk Awards, too. But even if it had not been recognized in its first production, I am totally certain- like you are totally certain in your hypotheses- that it would have been revived like 'Chicago' to a rapturous welcome, and would have had an equally long run, and would have been made into a lucrative, Oscar-winning movie musical!
Oh if only the producers had opted for Kander & Ebb...