The US State Department has just raised their warning for all travel abroad to level 4. They recommend that Americans avoid all travel abroad.
Airlines are very likely to start reducing or cancelling nearly all international flights to and from the US, so if you do want to fly back to the US you should make arrangements to do so now.
The US State Department warns, “In countries where commercial departure options remain available, U.S. citizens who live in the United States should arrange for immediate return to the United States, unless they are prepared to remain abroad for an indefinite period.”
Are you abroad currently? Will you try to fly home before flights may come to an end?