I am disappointed in the level of fear-mongering pearl clutching; it could[0] get so much worse!

First, the person creating the fakes is using an off-the-shelf algorithm[1], adapted accordingly.
A system designed purely for the purpose of swapping faces (or morphing a particular face into others, one-to-many style) would obviously yield improvements.

Secondly, it's the work of one person without commercial backing[2].
A studio that invested in lidar or used multiple cameras would be able to incorporate volumetric information.

Third, it's limited to individuals where you have a performer that's an approximate body double for the target in question.
Why involve real people at all?
That limits the kinds of scenes you'll be able to shoot, and it's clearly a production bottleneck besides.
Since it's feasible to create realistic animations of locomotion via deep reinforcement learning[3], applying the same technique would remove the need for human actors.

With that in mind, we can invent scenarios substantially more terrifying, for which this is but a teaser trailer.

As computation becomes cheaper and AI knowledge more widespread, the delay between when something becomes possible and when it becomes ubiquitous grows ever shorter.
Once custom pornography is just another something-as-a-service, the question becomes how do we optimize it? IoT sensors and wearables can provide the data needed to customize an experience tailored to your particular tastes on a moment-by-moment basis.
Facebook is sinister, but it's sinister in the sense of a malevolent external force with inscrutable goals; you can defeat it by not using Facebook.
The idea of a machine that can produce something more compelling than most stimuli available in the external world is scarier, because all it would be doing is giving you exactly what you want.

Okay, so the riff on wireheading in the style of Infinite Jest might not be adequately terrifying.
How about something more realistic, like character assassination campaigns?
We've seen how intimations of sexual impropriety can damage a politician's electoral chances or outright cause them to resign.
Sometimes, the thing that allows them to hold on to office is the fact that there's no convincing proof beyond circumstantial evidence.
However, if you've already primed the public with rumors, a fake sex tape might be the just the thing to push past the tipping point.
Imagine: a future where an individual could effect a bloodless coup using nothing more than a Twitter botnet to spread slander and a few GPUs to generate scandalous footage.

No? That's perhaps more in the vein of William Gibson.
The last thought that came to mind was along the lines of "the future is weird and terrible, yet somehow boring and familiar" a la Neal Stephenson.
The redeeming value of porn is that there's at least some intentionality behind it.
Real people had to be involved, from the actors to the crew to the guy who wrote the script in traffic on the way to the shoot.
The future will be endless porn spam, half-coherent plots generated by LSTM-char, just glitchy enough to be discernible as fake, yet seemingly unavoidable due to the sheer quantity made possible by automating the production pipeline.

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0. And when it comes to AI, "could" should be read as "will" but with an indeterminate time frame.

1. Apparently, the face-swapping is accomplished following "Unsupervised Image-to-Image Translation Networks" (paper: https://arxiv.org/abs/1703.00848 video: https://www.youtube.com/watch?v=Bwq7BmQ1Vbc), with the face detection provided by FasterRCNN.

2. The reddit account of the artiste in question: https://www.reddit.com/user/deepfakes (not exactly safe for work, but not particularly unsafe, either).

3. http://www.cs.ubc.ca/~van/papers/2017-TOG-deepLoco/