Rob: given the work you have put into these podcasts, I feel obligated to respond as you have asked listeners to do.
The book’s quality is evidence of your writing skill, technical acumen, and technological knowledge. As I listened to this podcast, it occurred to me that these podcasts have the feel of something — format, premise, purpose, etc., that has legs independent of your writing.
What to write about, etc; those are questions only you can answer. However, it is the sweep of your network that allows you to reach out and put people you know in front of a mic in a flowing, semi-structured, guided way. My 25 cents: stick with this formula; don;t dork with it unless/until this one demonstrates otherwise.
Next, finish the series you have planned…8, correct? Then widen the sweep of what follows by extending one or more of the first 8 podcasts into topic development — not deep dives. However, there is no shortage of things to talk about or examine.
There are numerous tech writers, but an insufficent number of males & females who present well with a solid colleagues network. Keep it going.