You mentioned California, so I am using that as an example. They would find it difficult to do such a thing. Other states with more reasonable approaches to taxes, might find it easier, but I'll denote the challenges specifically in California.

First off, keep in mind the following:

1. Populous states like California pay far more in Federal Taxes than they get in return in return. [1]

2. California must have a supermajority in the legislature to approve taxes. [2]

So it's a complex issue, but simply put, there's not a lot of wiggle room for California to add billions of dollars of health subsidies to it's state budget.

Medicaid is basically one big government subsidy for the poor. When the Obamacare medicaid expansion goes away, millions will fall out of health insurance instantly. [3]

As for the managed plans, subsidies were used to make the plans more affordable to the taxpayers which made it easier for people to afford coverage. [4]

It's possible that some things may stay in tact like the pre-existing condition clause, but unfortunately the health insurance companies won't be able to cover everyone without the individual mandate. [5] Also, before the pre-existing clause, health care companies were rejecting people for health insurance with pre-existing conditions. [6]

The options besides subsidies for California are:

1. Government mandate of costs at doctors offices and hospitals, which may become illegal if the US Congress votes against it.

2. Government mandates on the behavior of insurance companies. This might drive many insurance companies out of California.

Neither appear to be a viable option.

1: https://goo.gl/paMrzG 2: https://en.wikipedia.org/wiki/California_Proposition_13_(197... 3: https://www.healthinsurance.org/california-medicaid/ 4: https://goo.gl/JVkaN0 5: https://goo.gl/STciup 6: https://goo.gl/Uoljhx