In the future, when people start to question who owns most of the existing bitcoins, then better hope that there is another popular coin out there so you don't have to just withdraw fiat and game over. When people start to look into the amount of drug trade that went on with bitcoin in the past, and the amount of coins that have been reported stolen, then they will realize an important question: How to know if the criminal world isn't owning most of the coins in existence? People will question if investing new money into bitcoin isn't just filling the pockets of criminals who sold drugs and stole from others in the past. And then there will be one answer, that it's safer to start all over on a new platform that is not that suitable to the criminal element.
guaranteed that 100% of all cash has been used in some sort of drug exchange at one point or another...
Well, but cash isn't like bitcoin isn't it. Cash wasn't introduced with decreasing supply, where drug trade was the main market engine, while half of the coins came out in couple of years, with the rest coming in a period that is over hundred years

Bitcoin was designed mainly to reward early adopters and have a strong starting momentum by this. Most of the early adopters with bitcoin are in all probability different kinds of criminals. That is probably the reason why there are so few "whales" who like publicity.
We will be hearing this for years and it can get hot, but no, there will be no successful slavecoin.