Keep in mind that those users who do not want to lift a finger in protest are usually the ones who do not want to lift a finger to contribute. Not a speedy death, but with our new content those lazy viewers will grow bored and find another source. I don't think Reddit has a plan to replace the content. No new content and it will spiral down the tubes. But as some pointed out, the IPO will be done by then and the current administration will be out on their yachts when it does finally implode.
Users that do want to protest can edit all of their posts and delete them. Reddit will undelete them currently, but they pull back the edited posts. If people do this in small batches it won't set off any alerts and the site stops having any relevant content.