You are assuming current vaccines will be able to handle the variants currently coming about and those of the future. I don't believe they will be that effective or even partially effective on the variants so IMO B is going to be needed for a very long time as a therapeutic.
COVID-19 waning in 2021? Perhaps so, hopefully so. Financial Analysts who pin their names and reputation to the top of their commentary still see 2021 as a COVID-driven money maker. https://apple.news/A_6AjljgdQu6AM-_JhtbaBA
Maybe Brilacidin, through EUA gets a piece of the market. Maybe COVID-19, through mutations, roars back. Maybe BP, through foresight, recognizes the pan-Corona antiviral potential of Brilacidin and buys ahead of the next lethal zoonotic killer. Maybe the US, Europe, China, uncharacteristically, buy first-in-class Brilacidin to stockpile as a GDP-saver insurance policy.
In any case we won’t have long to wait. The efficacy of Brilacidin will be known by all before Spring gives way to Summer.