The increase in cost is sufficiently sub-linear that the cost of each new .org registration should be going down as the number of them goes up, if it was truly

The increase in cost is sufficiently sub-linear that the cost of each new .org registration should be going down as the number of them goes up, if it was truly run for public benefit while breaking even. As another comment says, most of the cost will be in building and maintaining a robust, scalable, attack-resistant distributed system. The linear scaling costs (such as bandwidth and processors) will be small in comparison. (Of course at much higher numbers, mathematically O(N) starts to dominate again, but 1 billion lookups per day isn't enough for that.)