In short, the risk is more of money coming from the bitcoin ecosystem being automatically treated as dirty money.

Yes. Also, governments won't tolerate further taxation and financial regulatory control being taken away from them (since that taking away is not paid for by lobbying) towards some kind of shadow economy. If it becomes large enough so that a random senator will know what it is, there'll be some guise ("drug currency") to control it, its viability for the US market will plummet, and once that's out of the picture ...