Hotels.Com already allows cancellation of bookings without penalty in many of the properties it advertises. But the unprecedented range of restrictions being placed on travellers, often at short notice, means that contracts are, to all intents and purposes, being frustrated by operation of law. It's not, in strict terms, force majeur although many are calling it that or, even, an Act of God. No, it's not that either.
Hotels.com has produced an excellent analysis of exactly what the US blockade of travellers from some parts of the EU means. The notice addresses many of the misconceptions and false arguments that are popular on much social media.