Given that bitcoin has a hard-coded cap of 21 million coins, if bitcoin became a reserve currency of the importance the USD currently has, you could assume it would reach a market cap of 12 trillion, meaning each bitcoin will be worth $570000.
The reason the USD value has not spiraled to $5000 each is because the economists advising the government believe in inflationary currencies, and believe for some reason that the best thing for a currency to do is to devalue by 1-2% each year. They give some reasons for this which, like a lot of economics are driven by conjecture and not evidence-based. Money is printed approximately to achieve this target, however in recent years, 4 trillion dollars has been printed and given to banks, again based on very little other than economic conjecture. I'm not going to argue with proponents of this sort of economic theory because its a waste of time, however I am glad that a currency not linked to a nation state is going to be able to challenge all of these assumptions.