No, Bitcoin will not replace Dollars. Bitcoin only will be a secondary payment option since most of people in the world even dont know to operate a computer in developing countries.
I agree with you but to some extent; currently bitcoin will continue to walk in the shadows of the US dollar as a secondary option but it will get to a time ( maybe generations after us) that everyone will be knowledgeable in computing and familiar with making online transactions; at that point it might be possible for bitcoins to replace the US dollar or any fiat.