Here is the idea presented by EffortCapital: Cosmos Hub Tokenomics - Fiscal and Governance Policy (Blockworks Research)
Please consider also that the cost for your calculation is only the basic infra cost, but you need people to manage and run nodes, perform upgrades, study and vote on governance proposals and a lot more, so real costs are much higher than those in your calculations. Considering the real costs only a few of the biggest validators are profitable now and after the inflation reduction. Most of the other validators are in a big loss today and would be in an even worse situation after the inflation is lowered