I believe that finding your niche in the world, whether we're talking business or not, is important but sometimes it takes a little time to find it. And once you DO find it and specialize on the tasks that you really enjoy doing, after some time it just might change because we're all growing and changing, and then you can choose a new niche.
Niche marketing allows us to focus our energies and resources on a specific market but we don't have to be limited to just one or that one forever. Nothing has to be permanent.