It's tragic that only the threat of a deadly disease could compel such a change, but perhaps we may find other levers to help us achieve such widespread beneficial changes in the future?
I am willing to bet that come 2022 or so, emissions will rebound and exceed peaks as people 'catch up' on travel, including simply visiting near and dear ones, that they have missed out on.
I think the lockdowns could be revealed as a costly mistake and there is a great hubris among the well off in thinking that because they aren't struggling everything is fine.
But this is particular argument is unsustainable. A lockdown can have generations of consequences - what doesn't? - but it cannot be paid for by generations to come. It was paid for now, resources were reallocated and consumed.
The risk is more subtle. If a group of people develop who have nothing to lose, then they lose nothing by being very violent and destroying stuff. Physical destruction of assets is something that can cause long-term damage. The lockdowns take away options from people who don't have many.