"My point is, more coca = more cocaine. Bolivians are not big consumers of cocaine now but they will be."
And my point is that if a Bolivian wanted to make cocaine, he could do that today(pre law change) for pennys. There is no shortage of coca in Bolivia, never has been never will be.
More coca will not make it any cheaper in Bolivia, it's not possible.
More coca will make cocaine more plentiful. Sellers of cocaine like new markets. Bolivia will become one.