You're right, it probably won't, at least not while it's still printing money for all the corporate entities involved. But it's my understanding that most of the data-harvesting tools in use today were originally created to enhance ad-targeting and drive up CPM. At the very least we can hope products like Blue might put a dent in this incentive structure.
Being relatively optimistic about Twitter's size, and assuming they're just fantastic at it, Twitter might make what, half of that? So for 3$ a month you need about half of the userbase to be on board for data munging to no longer make sense as a business model.
I do wonder how high that mark is though, every SAAS I've worked with has been pay-to-use from the start, so this is not a metric I'm familiar with.
What's weird here is that I would estimate it to be very difficult to find a person who generated over 30USD of revenue through ads for anyone other than the people selling the ads.
But maybe my worldview is wrong here, I'm definitely not the right person to estimate Facebook's reach.