There are people on your list right now, no matter how many people you currently have, that would make excellent joint venture partners. They have joined your list because of an interest in your topic, so reach out to them and see if they would make a good interview subject.
Connecting with the people who have found you online makes sense. We all learn from each other. Building relationships with others will be crucial to your success on the internet. I have now interviewed more than fifty people in the last couple of years that I connected with through my list. This has been good for all of us and resulted in joint venture opportunities I might never have had. You can do the same thing. It will help you to build credibility in your niche and give you people to interview for the others on your list.