Know Your Customer, requiring exchanges to provide the necessary data, etc.
Maybe Equifax has some engineers working on this right now for them!
http://www.cnn.com/2014/07/18/politics/irs-scandal-fast-fact...
That would work, I guess, but that is a huge step to make and governments aren't currently talking about how they plan in banning all of Bitcoin.
I can't see that ever happening especially because these protocols would have non currency uses as well.
Node software developers could be at risk, though.
An example: https://www.bloomberg.com/news/features/2017-11-15/the-final...