In fact, if we had had a centralized Rwanda-like medical drone delivery network in place, I think COVID-19 vaccine distribution would’ve been much better. (Although that’s as much about centralization and organization than it is about flying electric robots...)
Last-mile delivery to medical clinics at 80mph night and day, rain or shine, straight line ignoring traffic or geography is a pretty massive advantage for just-in-time logistics... it makes the concern about deep cold chain for Pfizer much less pressing.
I entered 3D printing 7 years ago professionally, but I've been surprised by how this has continually improved even in the last 5 years. Quality for entry level machines has improved dramatically and ease of use, etc. Which doesn't change your fundamental point that it'll remain niche. But there are some patents from Stratasys and others that will expire soon (it was a bunch of FDM patents expiring that led to the first wave of 3D printer hype starting ~10 years ago), and that should help expand the market significantly. But you're right we won't be manufacturing everything with 3D printing.
A lot of these things are over-hyped, but can still produce long-term value. Just not like trillions of dollars a year type of value.