Amen to all that, and congratulations on lovely prose. In a (long) lifetime of freelance writing, mostly for newspapers & magazines, I've published several nonfiction books and a zillion articles on every topic in the book. But niche? Nahhh. Recently I even self-published a collection of short stories from an MFA in short fiction 20+ years ago. Nicheing might enhance one's income, but going nicheless is a heck of a lot more fun. I think you just inspired a new essay, thanks!!