@mrb
What is the current usage of ZKShield in terms of transaction volume, can you please make this public in a simple dashboard (see Bloque) that can be easily referenced and also demonstrate progress of the product?
Sure, Can share some product images on how the product has evolved as a subcomment.

Does this usage (0.4-0.6% swap fees?) demonstrate a path towards sustainability of operations and development beyond grants?
Yes! There is a path to the sustainability for Kusama Shield as a product There is two fee's here that might be confusing:

• 1 - Swap fee's - This is to cover slippage by a third party swap provider. The Kusama Shield as a project does not earn a sustainable income for swap fee's until user numbers go up. You can view a demo of these swaps here: https://forum.polkadot.network/t/swap-60-different-tokens-straight-into-dot-on-the-hub/15988 . This enables the web app to enable user to easily come in from third party ecosystems. As Kusama Shield is one of the few products in the world that utilize the Polkadot AH dex to enable users to convert DOT to KSM, we are enabling a powerful onramp into KSM with low fee's. Part of the goal has been to enable users that use USDT on tron and assets in other ecosystem to bridge over and utilize Kusama Shield to get privacy at a low cost. Aiming to be a true web3 product

• 2 - Pool fee's the fee that you see in the image - This is the fee for inserting tokens into the pool - Because first iteration Kusama Shield was developed as public good - Extra fee's for depositing to the pool was not been added. This will be changed in order to make the product stand on its own feet. For example privacy pools charges the users when they deposit. Adding a small fee that will cover withdrawal transactions is a priority but we also want to keep fee's as long as possible in order to compete with other shielded pools that have raised million in funding.

What form would that income take (stablecoin fees etc)?
The future income streams for the shielded pool would be to charge a small 0.2-0.1% of incoming transactions and redistributing this to contributors. As of today if users use Kusama Shield the fee's are only transactions fee's by the Kusama AH network, making Kusama AH the winner.

Are new features a necessity? Feature creep has been a hallmark of most of the development done in the ecosystem - what is the absolute MVP to get to sustainability?
The new features as well as a future audit is absolutely needed. In order to provide a stable product that runs on PolkaVM, a lot of man hours needs to be spent in order to ship a stable product that can scale to a large chunk of users and also provide a great user experience. The project is not able to be self sustainable until a stable version and an Audit has been made since this very sensitive systems dealing with REAL tokens.Also keep in mind that several features have been shipped after V1 proposal was launched without asking for retro active funding. This v2 version is meant to take the product into a stable version where it can live autonomously on-chain forever.

The treasury is a common resource, therefore it should be understood that those requesting funds have an implicit responsibility to iterate towards value creation that can fund those that follow.
The Kusama Shield is constantly checking in with the community and 2 months ago ish a survey on the forum was posted: https://forum.polkadot.network/t/kusama-shield-v2-user-feature-survey/15435 this resulted in adding a privacy dashboard into one of the milestones

Thank you for the comments!