I don't think detection would really help even if we had it. Even now, most fake-news stories are obviously fake. They have no subtlety; they don't fool anybody paying even the faintest shred of attention.

They'll be used on people who are already perfectly happy to believe fake printed quotes from obviously unreliable sources. When challenged, they'll refer to conventional partisan media citing those sources as proof. Ordinarily showing video would increase their certainty, but they're already absolutely certain. It'll just be a more entertaining way of delivering it to them.

Detection, no matter how definitive, can't deter that. They're already perfectly happy with their trusted sources.