I'd love to hear your thoughts on the minimum desirable interaction here - is an API that just translates natural language to, say, SQL useful enough for you to pay for?
Definitely!
If you get the natural language to SQL right, then it is multitudes easier for me as a developer to parse a JSON and display the results to an interface than having to learn the natural language processing part by myself and then try to interact and implement with it!
EDIT: I wanted your email. Nevermind, I found it.
The tricky bit is going to be your enterprise sales channel, you need someone with the right connections.
It might be a completely worthless idea, but I would consider offering a "USB Stick" version rather than an appliance. It is much easier to replace, costs close to nothing, yet it can still be implemented as a self-contained blackbox with no customer serviceable parts.
1) they often have sprawling, disparate data sources, with schemas designed by deranged people in the 80s or 90s. The cleaner (and admittedly smaller) your data, the easier you can integrate, and to be honest, there's probably a hard limit at some point beyond which we couldn't provide value without doing bespoke customisation.
2) there are some fearsome competitors at the higher level of the market, who offer wider business intelligence suites.
This may be fear-based thinking though.
1) The more sprawling and disparate the data sources, the more deranged the schemas, the more money to be had making sense of it.
2) Enterprise consultancies are ripe for disruption. There exist exactly zero satistifed customers of these companies.
Most likely, you're just converting my questions into queries and parsing it over my data. Because your hompage is not clear if you are letting out just an API or you are giving out results of our data by yourselves. But if you gave out just an API, then it would mean we still have to process the converted queries and create our own interfaces to display the results. So I'm going to assume you take care of the data processing as well.
But, wait? You need access to my data to perform those queries. Let's say I have a million users. This means, you could potentially log every single query AND the result of the query into YOUR databases.
This means,
If I ask you "Which percent of my users pay the highest and are from the United States?"
And you perform a query on my one million users to find that out, you have data in your hands that my competitors or third party advertisers will come around you like sharks for. Whereas, all I can do at that point is just hope that you won't sell my data to them, which puts me and my data in a pretty vulnerable state.
Not to say that this is a bad idea. It's a brilliant idea, but I'm not sure how you are going to earn the trust factor.