Referring to the Boost FAQ written by Ariel a while back, I suppose the thing you can ask yourself is what topic do you have either professional or personal expertise in? That could be your niche. Unless it caters to too small of a group to matter. In my case LEGO is a very small niche and income is but 10% of my total, but I am willing to stick to it for another 1.5 years as I have first mover's advantage on Medium. Remains to see just how encouraging or disappointing the new MPP is. Either way, I suspect I'll be sticking to just a couple of articles a month by 2025.