Satoshi never said literally that he want to change entirelly the fiat money, but this is what it would lead to if Bitcoin would have been used as he created it. He wanted to help people to not be oppressed anymore by governs, by banks and by any other middle-men. To give people privacy and anonymity. To offer a way thus governs couldnt track anymore every financial transaction. To not pay taxes and fees to middle-men. To transact directly, peer-to-peer, without paying huge fees, as it happens (for example), if you send money in different countries / continents from your bank account or from Western Union. To help all the unbanked population.
This doesn't mean that bitcoin will replace or was intented to replace all fiat currencies completely.
Bitcoin was created to give people an alternative to fiat, for those who want price, freedom, etc. The world needs it, but as an alternative.
Unfortunately, very few people truly understood the meaning of the OP... For those who did not understand, check again
this post written by me earlier, in case you missed it. Maybe it explains better... I hope.
We understand but we don't agree.
Satoshi said we need a new payment system, and you conclusion is that this payment system will replace all fiat currencies all over the world completely. Big step , don't you think?
And what satoshi said or meant doesn't matter anymore. He doesn't own bitcoin, it is bigger than him.