The actual truth is even weirder: if Bitcoin takes over as the world currency, its value in $USD will be infinite, but the question will be meaningless, as the dollar will be worthless. Currencies tend to be winner-take-all within a society; if one takes over, its rivals lose all value, as their only value is in being a medium of exchange and store of value.
This is perhaps a contributory factor to the Bitcoin's volatility: if you actually believe it's going to succeed, unambiguously, the rational thing to do is to move all your wealth to Bitcoin. And similarly, if you believe it's going to fail, the currency by definition is worthless.
I think the US government tolerates crypocurrencies because realistically they are far more damaging to countries like Venezula and China who have much more restrictive economies and in those countries the flexibility of bitcoin is a huge advantage.
How many aircraft carries does bitcoin have? 0. Which (in my opinion) happens to be the exact same chance of bitcoin usurping the USD as a global currency short of some fundamental change in world power.
On the aircraft carrier issue - the killer app (literally) for cryptocurrencies is autonomous weapon systems. Imagine if you could deposit $Xm Bitcoins into an address and have access to a fleet of 100,000 drones on 10,000 speedboats. At that point, we're really in uncharted territory, though.
Who creates money is the best answer to your questions.