It can't be "fixed" -- not in the conventional meaning of the word. Obamacare is irrepairable; a total loss.
Consequently, the best fix would be to repeal it, in toto. Then,, start all over again.
There will be massive problems with this approach, too -- as you suggest. But every day of delay, part of the healthcare infrastructure erodes away -- and risks being lost forever.
Push the "re-set" button -- tomorrow, if possible -- and let the market figure out how to adapt and re-gain something like the status quo ante. Markets are really, really good at this -- and the less "guidance", the better.
I wish the whole thing would go away. You can accommodate for the relatively small number of people who have “enrolled” in an exchange. (Real enrollments or not, who knows.) They can invent a “Gold/Silver/Bronze Come All Ye Exchange People” plan to cover a couple thousand people.
It’s the 10-15 million people left scrambling who have an immediate need for some way to protect themselves. There’s not enough time left to put them somewhere. The day the insurers knew they’d lose that revenue and acquire all these new additional costs, affordable policies vanished.