Job loss is a qualifying life event under the ACA, so people can enroll even if the Feds haven't created a special open enrollment period.

For those who lost their jobs there are most likely three options

1) COBRA to continue existing employer-sponsored plan (if one exists), which will likely be expensive

2) ACA enrollment, which will also may be pretty expensive, but subsidized depending on income

3) Medicaid.

Yes to clarify, loss of insurance *due* to job loss is a qualifying event.