I would imagine in the case of another lockdown it would be because the situation has gotten pretty dire, new variant, vaccine no longer working....or potentially a new variant that impacts more heavily on the youngest unvaccinated in the population.
Not saying at all that this will happen but it is probably the only scenarios in which we would lockdown again.
Fundamentally, I disagree with this premise. I don't claim to know whether there'll be another lockdown or severe restrictions again, but I do not believe for one second that the bar is going to be something that affects children, iyswim. I think if we got something that was eg a lot worse for over 50s but still left children overwhelmingly unaffected, the possibility of a lockdown or at least enhanced restrictions would very much be there.
But in the event of there being something completely new, that did pose a higher risk to children, I'd act in my DCs interests as I have throughout. When I took the decision not to comply any more, it was more for their benefit than mine really, as I am much less affected by having to socialise remotely etc. When the state decided they were unworthy of a proper education and the ability to spend time with other children outside the home whilst thousands of others were to be permitted this, I arranged social contact for them with their peer group myself. When they were asked to isolate as a contact, we had walks and exercise outside when it was quiet, because it was reasonable, sensible and in their best interests to do so.
So I'd be making any decisions this winter with their interests rather than piss poor laws in mind once again. If it would actually be of more benefit to them to have their social contact and activity limited, I'll facilitate that. If it won't, not happening. Same principle, possibly applied to different situations.