If I am a Medicare-approved provider now, I am restricted to receive no more money than the Medicare-approved amount for any given service. If this Rand Paul bill were to become law, then the smart move would be for me to stop being a Medicare-approved provider -- because that allows me to keep serving my existing patients and still be able to get at least the Medicare-approved amounts for services I provide, but also allow me to ask (some of) my patients to pay me more. This bill will likely eliminate the incentive for any provider to remain Medicare-approved.
As eccentric as some of the old Ron Paul's view points were, I never really doubted that 'ol Ron knows economics. I don't have quite the same level of confidence with Rand.