Can nirvāṇa in a conservative sense called “eternal oblivion”? In a sense perhaps, one could.
Cf. “Oblivion, or eternal oblivion, is the philosophical concept that the individual self ‘experiences’ a state of permanent non-existence after death. Belief in oblivion denies the belief that there is an afterlife (such as a Heaven, Purgatory or Hell), or any state of existence or consciousness after death. The belief in ‘eternal oblivion’ stems from the idea that the brain creates the mind; therefore, when the brain dies, the mind ceases to exist. Some reporters describe this state as ‘nothingness.’ Many people who believe in an eternal oblivion, believe that the concept of an afterlife is scientifically impossible. Such views are typically held by atheists” (Wiki, s.v.).