I think a bigger question is whether reputable sources --those people trust for whatever reason, would use this technology to prop up ideas and or to create narratives.

I don't think it's far-fetched. We've already seen where videos are misattributed[1] to stoke fear or to promote narratives --by widely trusted news sources.

[1] This was foreshadowed with "Wag the Dog" but happens often enough in the media today that I don't think use of "deepfake" technology is beyond the pale for any of them.