The thesis is that all insurance is undermined with the latest pre-existing clause. Why? Well, the GOP wants states; to be flexible in opting out of ACA patient protections. If a state opts out,the argument goes then all patient protections are in jeopardy.
On top of this,let's lowball the estimate of people who lose their health insurance--34 million--but then the bill costs several hundred billions of dollars and significantly lowers the number covered. That's the economics you have to pay attention to in Ryan world.