We discussed a similar idea in reference to Godzilla, namely what kind of evidence we would need to believe that 'magical' elements existed in the world. The point you made then was that even something as outside our scientific understanding as Godzilla would be insufficient evidence to change our basic scientific world view, and that such evidence might not exist even in theory. I think this post could be easily improved by an introduction explaining this point, which you currently leave as an open question at the the end.