Broad or narrow niche?

Hey, hackers, I'm committed for the revamp of my project https://waitfeed.com, relaunch todos are already in progress, mobile apps implementation as well. Just was thinking that probably it would make sense to narrow a niche from "upcoming things like smartphones, tv series, movies, video games, electric cars etc." to only "upcoming tv series", but not sure if it makes sense and if my current niche is too broad. It would be nice to get your ideas, probably you narrowed your niche at some point in the past? Thanks