In this paper, the evolution of product differentiation in industries is modeled as the result of a cumulative cost-reduction process subject to spillovers in a differentiated oligopoly. Our results suggest that the long-run outcome is dependent on the intensity of spillovers and the shape of their diffusion function. With weak spillovers, firms dig their niche over time, differentiation remains important and cost-reduction keeps going. By contrast, if spillovers are strong and have a concave diffusion function, firms gradually use more similar technologies. This standardization process involves less and less investment. For spillovers of intermediate strength, complex technological landscapes may arise.