The thing is, the thresholds for when is what we're doing necessary & when it is it not... are ill-defined. We don't know the rules for when should it last forever and when should it stop. If the C19 mortality rates are down to ... 4000/yr? 20k/yr -- at what point do we say "Yup we can return to normal life now" No one is having this discussion.
My guess is that PPE use by all hospital patient-facing staff is here forever, now far more than what they did in past. Also a lot of PPE in GP surgeries and many other environments is a new forever thing. Possibly staff all wearing PPE in most care homes (and not just gloves) even though masks/aprons makes the job harder to do well. Forever.
Also that C19 will remain notifiable and trigger legal requirement to self-isolate, possibly for your contacts to self-isolate too. This will last for many years, at least 8.
International travel will become difficult for adults without jab documentation. Lots of MNers are saying now that's perfectly reasonable.
So yeah, some parts are with us pretty much forever, I think -- and I'm an optimist. Or someone who would accept 20k covid deaths/yr anyway.
CEV ppl may campaign for right to wear lots of PPE at their jobs routinely; transparent masks with face shields might be common sight on staff in schools, at least in winter. That won't be just covid related. It will be all diseases they want to avoid getting.
Mass gatherings could return... but There could be more licenses required for large events to be held, depending on the local disease status.
Encouragement to "WFH if you can" in winter illness season might continue strongly in future, which combines with economic strategy for some companies, anyway (less office space to rent or heat), and desire to not commute by many.
All This didn't happen in 1920s because people were more tolerant of harm/death and less controlling and less risk averse.