iPhone was going to be a niche product too if you remember Steve Job's announced market share ambitions when it was introduced. When you are introducing a totally different way of doing things, you invariably start out as a "niche" product. If it catches on, then the niche grows and becomes a major market segment. MBAir was also a niche product meant for the few people who were willing to sacrifice performance for mobility and what, hey! It's not a niche product anymore.