I’m from the UK and booked for September, but I think our situations have some similarities.
Greece has handled the crisis much better than either the UK or USA and are going to be very careful about reopening their borders and allowing people back into the country.
I did see a Greek (English language) newspaper article a few days ago that said the Greek government were in discussions with several other countries about the way forward and neither the UK nor the USA were included in this discussion.
My gut feeling, and I stress, this is just my gut feeling, having talked to friends in Greece and the vast number of discussions I’ve been involved with on Trip Advisor, is that it’s highly unlikely that visitors from either the UK or the USA will be allowed to enter Greece in 2020 as holiday makers.
I’m fully expecting my flights to be cancelled, at which point I’ll look into rescheduling for 2021, maybe September again, by which time (hopefully), the scientists will have created a vaccine and the world can get back to some sort of new normality.
As I say, not fact, just my gut feeling.