It's good and bad news. The bad news is that it will get harder to buy bitcoins anonymously. The good news is that mainstream business will be more confident in adopting bitcoin as a payment option now that the US gov has affirmed that it is legal. It wasn't illegal before, but the US gov had not taken an official position on it. That legal uncertainty scared away mainstream businesses and organizations. For example, the EFF accepted bitcoin for a while in 2011 but stopped, they said, because its legal status was uncertain. More businesses will accept bitcoin now, which will drive up adoption. On the other hand, this legitimizes bitcoin for us. If only drug buyers use bitcoin, then buying bitcoins is suspicious. But if lots of people use bitcoin for lots of reasons, there's nothing suspicious about buying it.