I don't know enough about everything else you said to address it. But for the timescale, he said the changes will happen in 4 years time. So they have enough time to do it properly.
Not really, no.
The NHS worked in the UK because there was a MASSIVE pool of surplus doctors from Asia, we hired, well, all of them, threw them in at the deep end and opened up free healthcare. This was for a relatively small country, the states are simply wanting to, even adding all the doctors from private healthcare, of which you'll find a lot of senior doctors choosing to take early retirement with plenty of cash to live off, simply not enough people as suddenly you're throwing 60/70million people into treatment with less facilities and no new doctors.
There isn't a spare pool of newly trained asian doctors to tap into this time, nor nurses, nor enough places for them to work.
NHS hospitals and only private hospitals are very different, private hosiptals aren't economical, they aren't run on wards but private rooms, meaning far fewer patients per doctor, meaning the buildings and facilities simply aren't capable of being economically viable to be "mass healthcare" hospitals where the goal is cram as many beds into a ward with as few doctors as possible to make it the cheapest it can be.
So there will literally be hospitals closing down left right and centre all over the states, yes new ones will open, but how fast and at what cost. Well infact they probably will use many of the private hospitals, and spend years and billions refurbishing them while they take massive losses and go WAY over budget.
Now, as someone on the BBC said after, if its a massive bluff and all that comes out of it is better insurance as the votes controlled by insurances companies agree to a bill thats inbetween a NHS and what there is now, thats a positive outcome. IE a comprimise is met where the insurance companies are so scared of a full on NHS they happily agree to lift caps in treatment and make getting treatment for pre-existing conditions much easier, and insurance much cheaper. That would be a big win, and ultimately what the states needs.
Remember, theres circa 40million who well, are said to be untreated, though anything immediately life threatening does get treated for free, but 40million who don't have day to day care for long term illness. But you've also got another 30-40mill people WITH insurance, or who qualify for healthcare who don't use it because the more they make claims, the more they pay next year, etc, etc, etc, the more problems with high premiums for pre-existing problems in the future. Same thing happened here, before the NHS, a bad toenail or a bit of a cold, people stayed at home. The second the NHS opened everyone and their dog went down to get checked out, we had extra facilities and a massive increase in doctors and nurses when the NHS opened its doors, the USA is likely to have less doctors, same amount of nurses as now, less building space and 50% more patients than seek treatment now.