Many people already fool themselves by simply refusing to fact-check anything that doesn't support their biases. If you thought "alternative facts" were bad now, just wait for this tech to hit 100% believability.
The disturbing fact is that this stuff is progressing in near real-time. A year ago these things were still totally unpassable. Now this Obama video could very easily fool a good percentage of people on mobile. I've no doubt it will be imperceptible within another year or two.