The only way it would get adopted for everyday use in the world/or usa, is if there was hyper inflation. I think that bitcoin will be more popular than paypal in our lifetimes, but it wont replace fiat in the near future, or hell, even in the next 100 years. We have to have something to give it value, right now, its worth 500 us dollars. if there wasn't a us dollar, what would you give me to buy it? It would take my employer to pay me in bitcoin, etc. so, I dont think it was made to replace fiat, just an easy way to control your wealth and easily transfer money. But Fiat is here to stay...
After the collapse of fiat, precious metals will become the main way how to value things again, and Bitcoin as convenient worldwide currency. I would take your gold for my Bitcoin, it would be complicated physicall trade, but once you get Bitcoin, you can use it so easily