(I am not a professional, so what I write below might be wrong)
Having more time to develop a vaccine or effective treatments is essential, it doesn't have to be herd immunity. Plus in countries where covid19 rate is low enough, social distancing can be helpful for finding and isolating clusters to suppress the epidemic.
Of course, there are two ways out of this, herd or vaccine. The above is a variation of herd that may result in less deaths.
The real problem is that waiting until a vaccine is just not even remotely realistic for so many reasons that it's not even funny. We could end up causing more indirect deaths with social isolation than we could possibly imagine, worst case being a huge collapse in the economy results in a large regional or global conflict.
Indeed, CDC's numbers for March indicate that social isolation is reducing non-ncovid-19 deaths by twice as much as sars-cov-2 is adding them. That's short term, so not what GP was talking about, but very significant numbers nonetheless.
How many suicides? Guys losing their businesses that they put everything into. Can't even go fishing without their fellow man ratting them out to Big Brother.
"How did it end?
The most popular theory of how the plague ended is through the implementation of quarantines. The uninfected would typically remain in their homes and only leave when it was necessary, while those who could afford to do so would leave the more densely populated areas and live in greater isolation.
Improvements in personal hygiene are also thought to have begun to take place during the pandemic, alongside the practice of cremations rather than burials due to the sheer number of bodies."
Having more time to develop a vaccine or effective treatments is essential, it doesn't have to be herd immunity. Plus in countries where covid19 rate is low enough, social distancing can be helpful for finding and isolating clusters to suppress the epidemic.