My idea is simple: Add-ons to Kagi that the individual user can pay for per month. There might be indexes and search resources that Kagi can hook into, but not worth to include in the normal plans because their APIs are too expensive. There might be in-house solutions made by Kagi, that aren't worth to include in the normal plans because they are too computationally expensive.
This feature is for specialists or other people who want or need access to special resources. It will not affect the work flow at all for other users.
A Kagi user who is an investor could purchase a Kagi add-on to integrate data from Dow Jones Fativa or Bloomberg into her search results, getting important insights into companies she searches for, or improved business news results.
A Kagi user who is a journalist could purchase a Kagi add-on from PressReader to have deep and broad news coverage in the results.
A Kagi user who is a careerist could purchase and be benefitted from an add-on that integrates the LinkedIn API
A Kagi user working internationally might want to purchase an add-on to integrate DeepL translations directly into the search engine.
And so on. The above are just imaginary examples. My idea is that paid add-ons can be a good option for when you don't want to include a source in the standard search function, instead of nothing.
This all requires that it would be relatively pain-free for you to integrate this with your payment and invoicing systems. If some add-on prove to be very popular, it could become a candidate for general integration into Kagi.
Thanks for reading!