Presumably they get desperate, then.
Look, it's easy to wave your hands and talk about viral articles, but fundamentally they will do what they need to in order to stay alive, or be replaced by a company that will. You can have micropayments (failed experiment), subscriptions, or ads. Empirically it seems like ads or other non-monetary consideration (influence, sponsored content, etc) has outcompeted subscription-based models for most content. Given that the "war" is entirely technical & visible to the end user only by the presence or absence of ads, the question is just whether you'll read a publication that has ads, or not. Empirically, the general population will.
(This says nothing about how invasive the ads are).