Bitcoin could just become the "Gold" currency by which all other currencies are measured. $USD<=>BTC
Why does there have to be 1 currency? Why not have a cryptocurrency that is completely anonymous and fast. You just created WhoreCoin, "the digital currency for ladies of the night". There's already a PotCoin. $DarkwebCoin. PayPal coin fails miserably and the company finally closes.
Design of any system is a tradeoff and is going to have flaws. Why not carve out a usage where the flaws don't matter? Bitcoin is a bit like gold. It was an early currency. It was heavy and hard to move around. All the people rushed to mine it literally or figuratively out of the "nothing". Let the price track like gold.
Then have it as the 'keys to the kingdom'. Pass a law that says the only legal cryptocurrency is Bitcoin and that only bitcoin$USD is legal.
Both sides win. Bitcoin is regulated, taxed, treated like a legitimate currency and then each corner of the dark web can have their own private currency and BTC(Private Currency) exchange boards.
Chicago Board of Trade and Chicago Mercantile Exchange, in an attempt to appeal to get the younger crowed excited in commodities, adds Bitcoin. It becomes another traded item just like pork bellies. (They remake Trading Places with Eddie Murphy and Dan Aykroyd as evil rich adopted brothers. Kevin Hart plays homeless scam artist. Chris Pratt plays a spoon fed Bitcoin analyst.)
Congress passes a bill that authorizes a $1M purchase of bitcoins to act as a pseudo central bank. Congress and old people feel like they've thrown 'plenty of money' at the problem. If you walked up to a random stranger on the street you might be able to sell them one for $5. Put 1 BTC on a printed wallet and walk around a retirement home selling them for $1 a piece after you explain what they are. Plus they'll think they have control over it. "$1M for a bunch of pretend money is plenty.".