I find all this concern a little bit overblown. Yes, it is a problem that we can make extremely convincing fakes, but we've had fakes that can fool non-experts for a very long time. The Soviet Union doctored a great many photographs in a way invisible to me (examples: https://en.wikipedia.org/wiki/Censorship_of_images_in_the_So...). Why are we more concerned about this fakery than about airbrushing?

The solution is the same as it's always been: stick to trustworthy sources and insist that all evidence is traced and corroborated. It remains easy to learn the truth as long as you make a good faith effort to do so. In the worst case we can just stop trusting photographs altogether. We got by just fine before the camera was invented; we can do fine after it becomes obsolete.