Ask HN: When launching to a small niche, should I already layout the future?

I'm working on a product that will be applicable for multiple audiences. I keep reading, and I agree, that it's best to launch to a small niche. But when doing that, should one already let people know that they'll be expanding to multiple audiences in the future?

Or should you tailor the entire product to that small niche and not hint at expansion into other verticals?