Your group health plan must notify you within 60 days of any reduction in benefits. If your employer has multiple health plans and discontinues most of them, you may be eligible to continue coverage in its remaining plan.
In most cases in which you lose insurance coverage because of something employment-related, COBRA gives you the right to continue your coverage by paying the entire premium for your coverage. But if discontinues all its health plans, you can’t get COBRA continuation coverage.
You’ll need to get your health insurance from another source. You might be able to convert the group policy into an individual policy. You might also special enrollment rights in your spouse’s group plan, or as an "eligible individual," which give you access to individual insurance.