This is like so many other once in a century sort of things, in that it's more or less impossible to prepare for until it happens. The 1917 flu epidemic was an entirely different world.

That being said, some relatively low-cost things that could be planned going forward might include:

1) Better stockpiles of non-perishable medical supplies

2) A National Guard-esque medical service made up of retired medical professionals, medical pros who go into other fields, and medically-adjacent fields like dentistry and veterinarians who can stay current on at a minimum level of competence in order to be called up in an emergency

3) Pop-up hospital capability. Places that aren't hospitals but could be established to provide emergency capacity on relatively short notice. I'm thinking hotels, convention centers, college dormitories, military barracks, etc ... where some combination of build code changes and tax incentives could induce developers and property owners to build in the necessary requirements. Kind of like fallout shelters during the Cold War.