My thoughts. As someone who is currently subscribed to the Pro tier ... this feels like a rug pull. Pro users would gain nothing in return, and still be expected to pay the same price, despite hearing multiple times that search + AI users cost less to serve than search-only users.
Prior to Kagi, I never used AI beyond the limited ChatGPT integration in Apple Intelligence, because I never want who I am to be associated with what I search for. That's exactly what happened with Google search, and I fear is what is going to happen if you use a model from the maker themselves (see ChatGPT's ad insertion). In the same way that Search's proposition is ridiculously good and private search, Assistant's proposition should be ridiculously good and private AI. As far as my use cases are concerned, that is how it stands today, and I have been a happy subscriber thus far.
I agree that there needs to be differentiation between the Starter, Pro, and Ultimate tiers, but I don't think this is the way to go. My suggestion would be to limit the Starter tier to Kagi Quick (or search-only if there must be a tier with minimal/no AI), Pro to standard models, and Ultimate to all models. In fact, I would like Pro to have access to all models as well, and if that means hitting the $10 monthly credit, then so be it. If providing that many credits is the real issue at hand, I would even be happy to have it halved to $5 credit. I find Assistant to be incredibly useful almost every day, but I only ever use $1-2 worth of credits per month. For that reason, I cannot justify upgrading to Ultimate. AI is useful, no doubt, but not worth an extra $15 USD per month for me. And, from what I can gather from the power users in this thread, Ultimate does not offer enough to justify a separate subscription. Not to mention the lack of mobile and desktop apps, nor API access.
I hope Kagi reconsiders this direction, and provides more concrete information in the future. At the very least, I thank you for making us aware of these potential changes beforehand.