A couple thoughts spring to mind including both your standard, “it takes a while to get everyone in to get one of these,” coupled with a growing distrust of expert medical advice.
A member of my own extended family is still convinced this is a giant conspiracy by [insert flavor of the week here] to [insert flavor of the week here]. I doubt that they get the vaccine no matter how fast it’s available.
I know the goal of vaccines isn’t realistically 100% deployment, but it feels there is going to be some lag here too.
My hunch is a return to normalcy looks more like everyone wearing masks in public for the next few years, with increased distancing in confined spaces (more sweeping WFH policies!) while we wait for adoption of the vaccine.