This doesn't work like that. You will have dopers in first (clean) league, because there will be all the fame, prestige and money. Unlimited league would be marginal and no one would promote drug users.
As to your unsupported statement that all the fame and prestige will be associated with the clean league, that is a matter of marketing. If there wasn't a market for doped up, super-humans athletes professional sports would be very different. Look at WWE, it's not even really a sport, but it takes in half a billion dollars a year on the promise of watching steroid guzzling guys throw each other around.
For many people the problem with PED is the dishonesty, the unfair advantage it gives a cheat. But when the stigma of cheating is lifted, all that changes.
A more likely outcome is that fans of some sports would shun PED and unlimited league events, others would see it as a natural extension of their attitudes about competition.