On paper, it's not that easy to find the Ignis main use case. The project covers a large number of different features and functionality, from an asset exchange to a compound phase. Because none of these functions are naturally available for Ardor, Ignis provides a lot of additional features, maintaining the security and core technology found in the NXT. First of all, it is a very technical project.
The project's aspect of mixing Coins is worth considering. While it does not provide complete anonymity, it is a privacy feature that allows users to mix their funds quickly and efficiently through random mapping. The similar feature today is built on NXT technology. This mixing is closely related to the Ignis monetary system, which allows users to create and trade user-defined Tokens on their sub-chain. All this “money” can be freely traded using the decentralized exchange feature or through external exchanges. This is a feature that any company that needs its own local currency in the future should focus on.
The progressive nature of the project allows transfers to benefit from deferred execution, regardless of the conditions associated with the transfer. For example, running a crowdfunded VC firm on Ignis is absolutely possible. Company shares can be sold on Ignis to raise money. It can also affect how payments are made between the VC firm in the loan portfolio and the ventures it invested in. Payments can only be successful if the majority of asset owners approve. Such specific conditions allow for many different business models in which most consensus-based processes can become completely decentralized.
Other than that, little is known about Ignis' future specifically, but I think developers will post more information.