You've mistaken the inner core of the market for the mainstream. This is a common problem, I find, largely due to terminology... While games like Pokemon do appeal to a broader portion of the market, they are not mainstream-appeal games. Don't get me wrong, they do sometimes create a market. But once the market is created, after the first iteration, it ceases to be "mainstream" and becomes a part of the core. The reason for this is simple: mainstream interests are not constant. In order for somebody to wish to see a successor to a product, they must believe that a successor is needed. A "mainstream" participant sees no need for successors; they live in the now of the product, and are drawn into the market by the uniqueness of that product. It is the desire for more, for improvement over what gets them into the market, which truly differentiates the mainstream from the core.
To put it in a meaningful context, the mainstream is "outside" of the market in a sense. By default they do not participate in the market, for whatever reason. To "appeal to the mainstream" is to draw a portion of a demographic into the market who were not previously part of the market. If you succeed, then they are no longer mainstream; they are a part of the market. Upon departing the market, they become mainstream again. This is the basic mechanic of market expansion and compression: the entry and exit into and out of the market.
Within this model, there is a level of core dedication. At the outer edges are the fringe of the market, where the most dedicated users reside. These users, frequently self-referenced as "hardcore", dedicate the most resources of any market participant, but are relatively few in number. As you delve into the market at large, you find the broader and less focused components of the core. Though the inner core (which paradoxically is not the hardcore but the non-hardcore) is large, it is spread much thinner dedication-wise than the fringe of the market. However, the deeper you go into the market core, the larger the userbase you find.
Whenever a market expands, it expands from the inside out, growing as less dedicated users are added into the mix, while other users "graduate" to more dedicated levels as they see fit. The fringe is always the slowest to grow or shrink, and the inner core the fastest. This is why you see explosions of new users whenever a market is disrupted: disruption translates to an authentically new demographic for the market, and the market expansion takes the form of the inner core of users growing at abnormally fast rates.
Sky Render - Sanity is for the weak.
