As someone who has a science background as you claim, you know it’s about numbers. It’s about when numbers are low enough and rate of spread is low enough that the public health emergency is over. You know that it’s not about throwing darts at a dart board or waking up one morning and saying, “You know what, Dr. Jill, It’s beautiful outside. I think today’s the day I’ll announce the health crisis over!”
Enough people have to be vaccinated to create herd immunity. Fauci - someone with a science background in precisely how this plays outs - doesn’t expect that to happen until the Fall. So, “well into 2021” is a logical estimate. I’m sure if numbers suddenly plummet in May and show every indication of staying low, they’ll celebrate that we’ve reached it early.
The problem with this whole crisis is that people *trained* in precisely this have been making recommendations or, sometimes, actually calling the shots, but others with a background in something scientific, or not background at all, have decided they know better.