You can't measure long-term immunity on a virus that's only been in the wild for ~11 months. That said, all the recent studies I've seen show no signs that immunity is going to drop significantly after a year.

I hate to link to a Youtube video, but this doctor walking through the research in the first part of the video is honestly better than any news article I've seen: https://www.youtube.com/watch?v=gFeJ2BqCFY0

Thank you for the link. The study definitely suggest a best-case scenario is viable. I do however think that the sample population of 183 subjects is too small to support the conclusion in the paper. The study only got a single sample from the majority of the participants andI couldn't find any indication of how many subjects from each location participated (or which locations were included outside of California), which makes me think it might not be a representative population used

I also noted that 40 of the participants were excluded because they had no PCR test done to confirm covid and no antibodies were found in the assay. This is in my opinion a major flaw, as the subjects could have been infected, but had no antibodies left, when the blood sample was taken

Finally seven of the 18 authors declare competing interests, which might have affected the research

Getting back to your post itself, I agree that you can't measure immunity for a longer period than the virus has been around, but that also means you can't say that there will only be a need for one round of vaccines, which was what I was disagreeing with

It might very well turn out, that you gain permanent immunity for a specific strain off the virus, but unfortunately that immunity also introduces selective pressure. Whether the virus is able to mutate in a way that bypass existing antibodies in a subject is obviously still an unknown, but we have seen that it's able to jump to other species like mink, which caused the emergence of the Cluster-5 variant

Since the virus is able to use other species as a reservoir and selective pressure is being introduced, I think it's reasonable to prepare for a scenario, where a vaccine won't be a permanent fix

Vaccines are not a great business in general. (Which is not the same as saying they're unprofitable.) But one reason vaccine makers are generally indemnified against lawsuits in the US, it that at least some companies would probably pull out of making vaccines if they weren't.