Why will it not? If in the future bitcoin keeps going up and fiat keeps going down which is what happens when they print more of it on a whim people might wise up. Money should grow over time not devalue and bitcoin could solve this and that's what's great about a deflationary currency.
I can see that you've got high hopes about bitcoin but dollar has been there long before bitcoin has been established but I don't think that it would replace USD anytime soon. We're a small community compared to the fiat and I'm pretty sure you know where I'm going with this.
I think that the Bitcoin is never going to to take over the Dollar I just do not see something like that happening. The Dollar is not doing bad so they do not have any reason to be taken over by the Bitcoin.