I've heard many say medicare will be bankrupt sometime in 2026. True or fear mongering, I don't know as I don't trust any of the sources telling me this, one way or the other.
In my mind, if all MFA is just a buy in, then it isn't MFA. MFA is everyone and yes, it means private insurance goes out of business or just offers supplemental insurance. I've already heard some seniors complaining that they paid into medicare all their life, now they going to offer it to others who haven't paid much if anything into it. They want their money back that they paid into it if everyone is placed on Medicare.
MFA is a political football that I'm indifferent to it. But I suppose the bottom line, is MFA means different things to different people and you get different definitions of it or how it will work from whomever you ask.