they always like to see a trial or limited early-stage release to at least establish the revenue potential.

Altera and the pools are live, we arent even early stage any more, we have proven what we can do.

anticipated future HBD grants from Hive ?

This is answered in the post.

and how will these be split between the development team, Hive, and other blockchains ?

There is no split between Hive or other blockchains. LPs, those that provide HBD liquidity and validators, those that bond Hive are primary earners.
Without the commitment in liquidity we are waiting for it is tough to anticipate revenue. What we need is between 1-3% of Thorchain daily volume to be selfsufficient and that would require significant HBD being bought and placed in pools.

what evidence is there that this will deliver a net benefit to Hive's user base and market cap, rather than being just a way for Hive users to extract earnings to other blockchains ?

The evidence is obvious and covered extensively inside the post. The second part reminds me of isolationism, that way of thinking is something i oppose completely and I dont think it warrants a discussion here. That is a discussion I do not think has a place in crypto. Its inherently defeatist and assuming it places us in a position of inferiority. And I do not think Hive is inferior to any other blockchain. Its a fundamentally different philosophy than I subscribe to.