We have canceled our trip to Europe like many of us. Our main airline (Virgin) is offering rebooking for no charge and we will be taking them up on it. Many of you will have similar options. However if you don't or like us can't use that option for low cost connecting flights there is an option that allows you to recoup some of your fare.
Taxes and other government airport fees.
For example I confirmed with Croatia Air that if I cancel my non refundable flight I can ask for these to be refunded , they will return those fees to my credit card. This is the regular policy, not in response to the Covid-19 issues. We will likely use this option because we would not be able to use the rebooking option within the dates offered.
Virgin Atlantic has the same policy stated in their conditions of carriage on their website but they do charge an administrative fee for this. Similar with Easy Jet.
I believe this is likely to be the case for most if not all European airlines.
I have not confirmed this with other airlines nor have I researched this with US airlines.
We are waiting until we are close to the flight dates on ours in hopes that the policies get more liberal ( seems to be happening to most of our flights and most airlines) and/ or the flights are cancelled . In that case we will get refunds.
But in any case going forward there may be some recourse now and in the future for non refundable ticket holders without insurance that covers your situation