Correct. This is an optimistic scenario for herd immunity. It assumes low mortality (probably true), no permanent damage to those who survive (unclear, but probably untrue), and immunity lasting a couple years (long enough to remain immune until a vaccine is available).
Doesn't this also assume that those people remain inoculated to further viral infections after being infected the first time? From my limited understanding, that is not a given for SARS-CoV-2.