The shitty thing about articles like this is they talk about "regulators" without finding any regulators to interview, without looking up any regulation to report on, and without investigating any pending regulation to comment about.
"Payments" is a whole lot more settled than "encryption" in the United States and, as always, it revolves around "pay your taxes." This is possible in no small part due to FATCA, the law that says "we're the US, we don't care where you're chartered, if you deal with the US at all we get to rifle through your files." FATCA shut down "Swiss bank accounts." Like, you either came clean or you moved to Liechtenstein, which has really shitty banking laws (if you want privacy, you make your banker your trustee and give him 100% control over your finances with no way to claw it back if you don't like what he does - in fact, he can keep all your money and you can fuck off). This is one reason Nevada, Delaware and South Dakota are tax havens beyond the imagination of the Panama Papers: being domestic American states, they are exempt from FATCA.
Current crypto legislation is all about "pay your taxes". More than that, the last go-round literally said "if it's less than $600 we are forbidden from ever asking about it." And it's not $600, it's "whatever the W2 threshold is at any given moment." Not only that, but person-to-person transactions of any size are legally shielded from scrutiny.
Because the other side of it is any payment between a bank and you over $600, that is on any blockchain, needs to be public. And again - that's the BANKS, not the citizens. They want the onus of reportage to be at the onboarding and offboarding. Not only that but they have said that public blockchains are the same as SWIFT for purposes of money transfer - Comptroller of the Currency is 100% fine with it.
The sticky thing right now is that the federal government hasn't decided whether cryptocurrency is an equity or a commodity. They're firmly behind the idea that it isn't currency because it isn't a reliable store of value and it is not backed by a sovereign nation. However, the CFTC and SEC are pretty much tilting towards crypto being a commodity, which forever walls it off from ETFs and the like, and which puts it in a different tax regime. Which is the whole point - from a tax standpoint, buying something with bitcoin is the same as a trade-in-kind and the taxable value gets assigned at the time of trade, the end, no fuss no muss.
Once crypto is firmly in the commodity camp, whatever Signal is doing isn't a "payments network" anymore. If you exchange goods across the network as a private citizen the government is no longer entitled to care about it. However, if you exchange money for those goods, the exchange point is reportable. They monitor your banking records, same as they always have, with much higher transparency than they've ever had before.
That's the thing that people are stupid about - the US government wants you using crypto SO BADLY because it's so much easier to trace than cash or gold or whatever. They can have an algorithm watch your ass instead of a forensic accountant. Yeah there will still be crime, there will still be petty crime, there will still be grand crime, but in the end how much do you think the treasury really cares how you pay your dealer? They're far more interested in how the Triads launder their prostitution earnings, and that becomes much trickier if crypto becomes the coin of the realm.