I get how this could be a problem, but it seems to me that it would only be marginally effective instead of exponentially as some assume. The reason I think this is because we already have this kind of thing going on without AI [1]. And while it does work, it's not clear to me if making the fake more realistic actually does anything for the kind of people who get worked up about this. If you want to claim Seattle is burning and it's not, just grab a picture of another place burning, and you're good. Narrative achieved.
If you can pass as authentic a photo from a different place taken at a different time, then what does it matter if you can generate a new one? Are you going to trick more people? Maybe. But I have a feeling the people who are most likely to get tricked, would have been tricked by far more mundane fraud.
[1] https://www.rollingstone.com/politics/politics-news/fox-news...