With zero income on the exchange I believe you would be put on Medi-Cal. There is no asset test. You can look at the covered California site to see what the minimum income you'd have to have on your O-MAGI to have a regular ACA policy.
Use this link and you can compare your current policy to what is available at zero and maybe a higher income if you could sell some stocks or do some Roth conversion or whatever -
Personally I like the Bronze policies with an HSA, though we can use the tax deduction the HSA provides.