Its only a rough estimate here, but depending on the native chain the treasury can either be a module in the main blockchain, or a “sidechain” type of deployment using shared security. In the hub’s case I think it’s safe to say we’ll go for a sidechain to keep the hub as minimalist as possible.
On that case the cost of running that chain is the same as any chain it’s the cost of running the validation process which is arguably negligeable considering the hub’s marketcap. I don’t have the real numbers here but a validator instance on a cloud can cost between 500-2500$ multiplied by the nb of validators.
However, on the return side the value is easy to understand. We seriously increase the governance decentralization (as explained in this paper) while also reducing the cost burden of delegators. In that system the governance organs are funded by their referring cohort (validators pay for validator councils, etc…). This seriously increases the accountability of the councils; They will have to bring value to their cohort otherwise they’ll be defunded and replaced by more productive alternatives. Imho this system is the best I’ve seen so far to incentivize cost optimization of governance. The only additional cost can come from deploying a new chain on shared security instead of a module ran on the mainchain. But on the hub’s case, the minimalist approach could definitely justify the cost. It’s up to the community to debate on that front. I’m personally OK with both options