I hadn't seen this mentioned so I wanted to chime in- the official statement from Homeland Security says that the Europe flight ban does not apply to "legal permanent residents, (generally) immediate family members of U.S. citizens, and other individuals who are identified in the proclamation."
So Americans who were already in Europe when the ban was called will still be able to come home. My family is there on a trip to Finland & Estonia right now. They will have to cut their trip short but they will be able to come back to the States. What we don't know is if they'll be asked to self-quarantine when they return. They live in a fairly rural part of the Midwest, but the college campus about 15 miles away from them has already cancelled in-person classes so the area is kind of on high alert.
Here's the full official statement if anyone hasn't read it:
https://www.dhs.gov/news/2020/03/11...-f-wolf-s-statement-presidential-proclamation