Yep, you're right. At 5$/month they'd need 6.66M subscribed users. Still a lot, but more acheivable.
The problem is that micropayments are not interesting for most news outlets: the friction of current solutions is high, the resulting revenue stream, unsteady. Monthly / yearly subscriptions bring a better revenue stream, and cost way less.
If micropayments were indeed zero-friction, and effectively zero-cost, maybe they'd be (reluctantly) integrated.