What happens with the tenant? The buyer will inherit the tenant. He will honor the lease or buy the tenant out. Your buyer has not made an empty house a condition of the sale. Monday at closing will be the wrong time to tell you about it.
Because the new owner would inherit the T and the lease, I would say that the new owner could evict the T for holdover if the T remains after the end of the lease. IF there is no provision in the lease for the LL to provide a termination notice.