In my opinion President Trump needs to get the insurance companies on board with some assurances on premiums. That seems to be the missing link here, the fear of escalating premiums.
... To which they’d say, without healthy people in the plans, the premiums will go not just through the roof, but through the stratosphere. That’s why the insurance industry wrote the ACA to include the mandate. It made them billions and, they’ll say, kept the premiums lower than if there was no mandate.