Hypothetical:
Pepsi starts using AI in some magical way that allows them to increase their margins. This allows them to reduce prices while increasing profits. Price-sensitive customers switch from Coca Cola products to Pepsi products. Coca Cola loses some market share, reducing economies of scale, and reducing margins, thus reducing profits. As the cycle repeats, Pepsi moves to dominate the market, and Coca Cola is slowly squeezed down.
Realistic and historically accurate:
Pepsi starts collecting the extra profits with zero price reductions.