In general, a Medigap Policy will not cover things like long term care, dental, vision care, things like eyeglasses or hearing aids, as well as private nursing care, as in a private duty nurse.
Non Medigap Plans
There are insurance plans which are not a Medigap plan as in Medicare Advantage Plans. This could include PPO, HMO, or a Private Free for Service type of plan. Medicare Prescriptions Drug Plans are not Medigap, as well as Medicaid. FEHBP which is Federal Employees Health Benefits Program are not. Non Medigap also includes TRICARE, or Veteran’s benefits, any long term insurance policies, Indian Health Service, Urban, Tribal, Indian Health Plans.
Dropping an entire Medigap policy including the drug coverage should be done with caution. Especially when it comes to the time. You may want a completely different policy, with or without a drug plan, possibly a Medicare Advantage Plan which would then offer a prescription drug coverage as part of the plan.
You may have to pay a late enrollment penalty if or when joining a new Medicare Drug plan. Prescription Drug Coverage that is not a credible plan or going over 63 days plus successively, may cause you to pay late penalties.