Absolutely @howtostartablog, although you can be "niche" and still have this area of expertise include a presence on several channels/platforms. Ie, @jerrybanfield is arguably an expert in the field of cryptos, Steemit, and most importantly marketing...and he displays his field of knowledge through all the income streams he describes in this post.

That said, if by "niche" you just mean a few different streams, then that's exactly what I'm trying to do here...first focusing on Steemit, then as Jerry suggests in his response to me, other avenues will evolve naturally (if I understand him correctly) -- >

"On the blog in the comments as you have done here the opportunity to collaborate with others will come perhaps in the form of clients or perhaps demand for videos, books, or other forms outside of the blog that readers would like. "