Another good point he made is about how he's calculating this. He's projecting current usage into the sub model.
But he's probably very right that casuals will probably leave and power users will probably pay. So it's the Spotify problem, your power users use you more costing you more but they don't pay more so you start going in the red. Considering relay is not a VC backed app or anything like that. One miscalculation and one bad month and you could see thousands of dollars in surprise costs.
Go to the bottom of the page, click on the Instances link and you'll se 2 lists, all federated instances and all defederated instances.