[shuntress]

For most people that's true but for extremely high profile like Barack Obama, Jeff Bezos, Bill Gates, they will have other channels to confirm their identity (and their current public key).

If you want to stretch to the logical extreme full-dystopian deepfake future where any message could be fake then the only real solution is the free press. A distributed network of groups and individuals that will each independently validate the things that people do and say then make those validations available for the general public to review.