Ask yourself not whether there is a leader in the market, but whether that industry is in flux and whether the buyers in the industry are apt to seek and adopt something new.
If you don't get the sense that things are fluid in your target market, then I'd recommend staying away. In some markets people just don't like change.
IMO it's not about whether there is a leader, or whether it's an untapped market, it's all about how the market reacts to new things.
Look for reactions to other products in the same market on social media. Was there excitement? apathy? Why? Consider this a preview of the kind of reactions you're going to get. If you don't like it stay away.