Bitcoin could replace the money but its from now real far a way if you ask me, due to the reason the bitcoin has to get a lot bigger if this would happen. I think with the future of the bitcoin is possible but it will take a couple of years maybe even more something near the 10 years.
Even if bitcoin gets more popular and bigger in future its unlike to see that it can ever replace a paper money which has support from the Government and the society and bitcoin will be always used as an secondary currency.
Yeah it's a bit unlikely that btc will "replace" paper money. As it will be almost impossible to have governments shift their support from what is generally being used for a very long time to something that you can't even hold in your hands.