I hate to say this, but Bitcoin is too small overall in order for it to be the currency of -whatever-. And I don't mean small as in user base, I mean the divisions are too small.
As it stands, if every satoshi was worth $1, the market cap would be ~2.1 trillion, if I remember correctly, and thus would be too small to replace the current monetary system. Hypothetically it could, but there would be too many outstanding debts, or anything really, in order for it to be able to fully integrate itself into society.
The choice of 8 decimal places is arbitrary and can be changed, without diluting the value of Bitcoin. Your math/memory is also off. If each existing satoshi was worth $1, the total final market cap would be $2.1 quadrillion.