The topic of subscription ceilings, or peak subscriptions, has come up a lot in conversation recently, but after a chat with the HBM Advisory team it seems the problem has been misunderstood.
For Alan Hunter and Michael Brunt, the concept of a subscription ceiling isn't about there not being enough potential subscribers to convert, nor is it about readers avoiding the news, or not having enough money. Instead it refers to a point where a publisher has saturated their core audience, where cost-per-acquisition becomes too high. There are still plenty of potential subscribers, but the publisher needs to build out their offering to reach wider than their core audience.
In short, it's not a problem with readers, but a problem with publishers.