Even assuming we live in a world where there is a reasonable hope of eradicating covid with the vaccines that we have, it still wouldn't be enough to simply rely on a gentleman's agreement for various parties to implement mandates. Different parties have different incentives, and even dictatorships have to spend political capital to impose policy. And if the imposed policy turns out to be much less effective than promised, there is even less political capital to impose the next policy.
Moreover, it is unclear to me what point the OP is making about the list of potential downsides of wearing masks. Perhaps it helps to already know his position on that matter?
Even assuming we live in a world where there is a reasonable hope of eradicating covid with the vaccines that we have, it still wouldn't be enough to simply rely on a gentleman's agreement for various parties to implement mandates. Different parties have different incentives, and even dictatorships have to spend political capital to impose policy. And if the imposed policy turns out to be much less effective than promised, there is even less political capital to impose the next policy.