It will become even more apparent when the population is primed to believe it, pick your hot button issue of the day and some significant portion of the population would absolutely believe a fake video depicting the opposing party doing something horrible, without pausing to reflect.
Even seemingly harmless caricatures, like Tina Fey's infamous SNL skit of Sarah Palin ("I can see Russia from my house"), have a long term affect on people's perception of reality: http://eprints.lse.ac.uk/59838/1/USAPP_Blog_In_politics_cari...
In that paper a survey found that 7 in 10 Americans believed that Palin actually said that.
The mass production of deep fakes will have a deep and profound impact on society. I'm not keen on where this is heading.
But it definitely depends on the news source and how thorough they are with verifying stories.
Photoshopped images are a sort of "trial balloon" which has already proven that the system is pretty dang robust, that's my thesis.
what if you see satellite images of a country mobilizing or testing nuclear weapons? What if someone synthesized sensor measurements?
Another example I could think of is a highly sophisticated spearphising attack. What if someone impersonated a boss's voice over the phone? What kind social engineering/manipulation could that type of adversary get away with?