Proposals, such as medicare for all, that push to eliminate private insurance make it plain what the goal is but also set up the attack that you cant keep your plan/doctor. The attacks will have to be addressed both before the plan is enacted but also after and even after the provisions take effect. Those attacks will be used against Democrats and if successful against the plan.
Proposals like buy in delay the issue. Some employers would like the option of pushing their employees into the buy in if it is cheaper for the employer. Large companies have self funded plans that are administered by private insurance companies so the buy in cost would have to be less than the internal cost plus admin cost to make sense. I think thats possible.
As an employee I might opt for that or might want to pay more to keep my doctors in the current plan.
One thing buy in has to address at some point are the low wage workers who are currently screwed by employers who limit hours to avoid having to provide insurance.
It isnt clear what the market might look like 5 or 10 years after the provisions kick in. If single payer saves as much money as believed we should see some of that benefit with buy in which makes further steps to push people to MFA. If the implementation is shaky at least we might stay in power long enough to fix the problems.
I like being able to make some big improvements over the next 5 years and then start working on the next steps that make sense. We should also be pushing for prescription price reform independent from the other parts of the plan.