Did someone here embrace "This won't work. Therefore, nothing will work. We should do nothing!"? I don't see that in this thread, but feel free to point it out if I missed it.
I simply started with a seemingly easy question: who decides what is and is not fake news? Trying to answer that question yourself hopefully helps illustrate just how challenging it is to find a solution that isn't worse than the problem. But hopefully with enough pondering on that question, one does start to lean in the direction that any solution must include individuals ultimately deciding for themselves what is and isn't fake news.
Does that imply nothing will work? For sure it does not. But it might imply we are already there: the best cure for fake news might be working harder to make real news more persuasive. It could be a boring matter of will and effort - a lot of grunt work. By talking to the journalists engaged in that work, you would uncover the actual challenges and perhaps ideas around the technologies that could better empower that change. Or not. The internet itself was supposed to help us become better informed. Clicks + adverts + automatic measurement, rinse, and repeat; proved that ideal wrong. At least for now.