Can your medicare supplement provider drop your coverage?   If your policy was purchased after 1990, then no.  The medigap policy is guaranteed renewable.  The only way your coverage can be dropped is if you stop paying your premium, information you provided on the application was not truthful, or the insurance company goes bankrupt.

If  you were to lose coverage due to bankruptcy, there is protection for you.  You have 63 days from the date your coverage ends to purchase Medicare Supplement Plans A, B, C, or F.   This is referred to as a guaranteed issue period.