One thought: do we need herd immunity at all? Wait, hold off pushing the downvote button.
Why is this virus a problem? Not strictly because of deaths, although one would want to avoid unnecessary ones. It's due to the pressure on the healthcare system, because many people end up hospitalized, even though most of them recover (more on long COVID at the end of the post).
The vast majority of people ending up in hospitals are also belonging in the "at risk" population. To relieve pressure on the healthcare system, these must be vaccinated (along with healthcare workers). But once the most vulnerable and the most at risk of hospitalization are vaccinated, the pressure on the healthcare system should lower or cease for the most part (and the early data from Israel seem to indicate just that).
Of course, vaccination should continue (for those who want to get vaccinated), but with the risk of overwhelming hospitals gone completely, it would not be a problem. So society should reopen. And yes, in this case the virus will become endemic (it almost is already, save for a handful of places).
What about the others? Aside those who vaccinate, those recovered who did not have serious complications can go on like normal, like everyone else. According to data from Qatar[1] the risk of reinfection is low, and, most importantly, the vast majority of reinfections are asymptomatic (and asymptomatic people spread much less than symptomatic people, FTR[2]). In the context of the virus mutating towards (in the timespan of years, rather than months) completely escaping immunity, it is much better to rely on a combination of vaccination and natural immunity, so that subsequent, possible reinfections are not severe. That would also give time to adjust the vaccines if need be.
Unfortunately even throwing natural immunity along with vaccination is now a taboo topic, given how politicized the debate has become.
"What about long COVID?" some people may say. Well, the problem with long COVID is that, while it certainly exists, it is poorly characterized. Most studies lack a baseline before infection (or rely on self-reporting), so it is hard to determine what and for how long happens after an infection. Lastly, "regular" pneumonia can actually wreck someone for months or even a year, and some of these issues we're seeing may due to that: we're just seeing them at an increased rate because more people are experiencing that.
[1] https://www.medrxiv.org/content/10.1101/2021.01.15.21249731v...
[2] https://jamanetwork.com/journals/jamanetworkopen/fullarticle...