But seriously that depends on many factors. Nobody would order more. First action would be to get rid of the stuff by lowering prices or throwing it away. Or if it is too late they would declare bankruptcy.

Unless both products had the same amount of sales and generates the same amount of revenue, the lowest seller with the lowest margin would be cut.

If there’s a replacement product somewhere it might be brought in and the cycle would start again OR the shelf space of the “winner” would increase to take over the now empty spot if the products were shelved in the same set.