(shifting my tone from trying to disagree with you to one of genuine curiosity as you clearly know more)
I have read many many experts say that we do not know how long immunity will last but that we can expect done immunity. No one has gone on record as strongly as you seem to be. Are they being conservative, or are they just wrong?
Here is one example of the types of things I'm reading. Do you agree/disagree?
https://twitter.com/NAChristakis/status/1240689935557865472