I saw a worthwhile (IMHO) opinion-piece about this proposal in the Wall Street Journal a few weeks ago.
-- The most immediate problem with the proposal is (no surprise!) that it is all indulgence up front, same as Obama's PPACA, and paying for it is neglected until much later.
-- As an explicitly mentioned example, under the current CA proposal anyone can go to any doctor or hospital for anything, and the state will pay for it. No gatekeepers, no cost controls.
-- We can therefore guess, correctly, that very soon the costs and cost growth will exceed the state's ability to pay for it.
As a semi-parallel, many years ago I exchanged emails with someone in Alberta Canada. The starting point was that when Alberta started their Medicare program (their name for Canada's single payer) they did the same thing. Show up and get treated, the province will pay. They got flooded by people coming up from Montana for the free care. They had to issue Medicare cards to those who would be covered, and others (Montanans) would have to pay money. He thought it reflected shamefully on America and Montana that we don't also provide 'free' care. (It still costs money, so it's not 'free'.) I thought that it reflects the lengths people will go to to get something for 'free'.