1) This effective backlash/education-campaign has not already happened despite there already being significant problems with this kind of thing, and most of it not being that hard to spot, even, and 2) I think the more likely effect is the destruction of shared trust in any set of news sources—we're already pretty damn close to this being the case, in fact. "It's all lies anyway" is a sentiment that favors dictators more than it does democracy.