Any "losses" will just be made up in other markets, like heroine. Like any businessman, if you loose part or all of one market, you find another.
But to think that the government will have "reasonable taxes" on MJ, or coming soon, ANY SIn tax market is absurd. As for the size of the alcohol bootleg market, I don't know. I would imagine it's comparable to the Canadian illegal booze market, adjusted for population of course. Billions probably. And I don't mean home brew, but offshore untaxed "good stuff" smuggled ashore. Check the government BATF web site
The cartels are ALREADY moving cocaine and heroin and meth to the tune of about $5 billion. Demand is ALREADY being met. There simply isn't the upside left to replace $8.6 billion.
But to think that the government will have "reasonable taxes" on MJ, or coming soon, ANY SIn tax market is absurd.
States are hurting desperately for revenues. If they legalize pot, it will be for that reason. Therefore, it is in their interest to tax wisely.
It's been done with alcohol, so it is not as absurd as you maintain.