One could make a case that all ministry is niche ministry.
The church we attend and are beginning to love - Crossway South Florida - wants to be "a city within the City for the City." Not for all cities. We're focused. And that's good thing, living within our limits.
You can't reach everyone at the same time. Segmentation is a consequence of God's generous gift of human finitude. To deny the existence of limits is to deny our place in the world.
Maybe the question isn't: to segment or not to segment?
Maybe we need to ask: what's a God-honoring way to segment?