This is the sort of thing that I can't even imagine what the upside is. This pisses off everyone, from the poor and sick consumer to the multimillionaire insurance company CEO. Literally nobody wins.
Actually there is a clear winner: Doctors! They would no longer have to deal with Medicare, Medicaid, and insurance companies but would instead be paid immediately (in cash!) via HSAs. This is the political equivalent as if Herman Cain made his first policy announcement as making weekly pizza consumption mandatory.
This show that Carson is truly just winging it on his own. If he actually had any policy advisors they would have stopped this lunacy.