There is no question that success stems from the exploitation of a unique strategic position. Unfortunately, no position can remain unique or attractive forever. The firm lucky enough to be in one will be imitated by aggressive competitors, and, perhaps more important, supplanted by even more aggressive competitors, those which develop new strategic positions in the market.
New strategic positions keep emerging all the time. A new strategic position is simply a new viable who/what/how combination perhaps a new customer segment (a new who), a new value proposition (a new what), or a new way of distributing or manufacturing a product (a new how). Over time, the players with the new positions will rise to challenge the status quo the firms that have grown too comfortable in what once were their unique positions.