Sounds like you have a great discussion indeed with the partner.
I would say the last question that the partner gave aimed to test your ability to think beyond the framework you have used during the discussion. The flexibility to comes up with different reasonings are crucial in consultancy line. While it would be perfect have you been able to mentioned at least 1 or 2 alternative methods, I would say it should not affects your chances negatively (hopefully you have indeed mentioned some form of ideas in response to such questions in the interview which would be an even better case).
What would count more in partner level interviews are the fit questions (or the PEI - Personal Experience Interview). The partners would take a comprehensive view on the fit results in combination with your case performance to come up with the final decision. As your explanation does not include the fit part, I presume this goes well and hence the reason why the partner would summarize the discussion as being fruitful.
In summary, I would stay positive on your result. You have done your best in the interview and the partner has supported your conviction through the closing statement. Come what may, I believe you will got the best option in response to your hardwork.
Hope it helps and fingers crossed on getting the decision soon.