The problem with AstraZeneca is that it's gotten a bad rap already a couple of times. First, there was the test data problems where they screwed up the dosage on one of the Phase III trials. Then the numbers came back and some countries restricted the vaccine to people less than 65 years old. And now this. While AZ might be an effective vaccine, it has some serious PR problems. I've read that in Germany they can't give the AZ vaccine away - and now they've halted all AZ vaccines due to the blood clot issue.
Look at it this way: If you are given a choice between AZ and either Pfizer, Moderna or J&J, would you choose AZ? I don't think many people would.
So the problem that the US is going to have is when AstraZeneca gets around to applying in the US for emergency use authorization, does the US approve it? Knowing that most Americans aren't going to want it, and we have enough of the other vaccines to cover our population?
If the US doesn't authorize it, that would likely be a death knell for its use in third world and second world countries. I suppose the US could authorize it, and then just ship our allotment of AZ doses overseas for other countries to use. That might present an image problem however; the US keeps the top tier vaccines for itself and ships the second tier vaccines to poor countries.