I do not think that bitcoin will ever replace the dollar, because it is only a digital currency in contrast to paper money and the world government will not allow the bitcoin to destroy its wealth.
Agree. Bitcoin won't replace the dollar anytime soon, since it has many issues underlying it, not to mention that governments would want a currency that they would control and manipulate, where the pioneer cryptocurrency is decentralized in nature.
Therefore, a currency whose money supply cannot be manipulated, like Bitcoin, cannot become the next dollar. But, I do know this, and that is that governments like the US are devising ways to transition from physical fiat dollars to digital dollars by exploring the blockchain technology.
When governments start rolling their own blockchains or a global blockchain with their own currencies, then they will stay in par with current cryptocurrencies and co-exist for many years to come.
It would be an interesting fact, if Bitcoin continues to survive for many years ahead, as forks continue to emerge. As long as it remains strong, it will be seen as a secondary payments system besides fiat to transact in this highly evolving world. Just my thoughts