And actually replacing dollar is not even the aim of making bitcoins, bitcoins were made like an alternative secure, anonymous and yet transparent currency where users control them and don't have to pay taxes. Added to this exploring awesome features like gambling, etc for worldwide users. Though replacing or dominating dollar would be a milestone.
Agree. As Bitcoin was made for the unbanked, I have no doubt that it may replace the dollar sometime in the future as it becomes more scalable and accepted worldwide. Since you have control of your own funds, it makes it somewhat safer than fiat itself considering that you only need the private key in order to access your funds, anytime, anywhere with no middlemen and very low fees. It has so many advantages when compared to fiat currencies like the dollar, that if it continues to increase in popularity, and widespread adoption, it could really become the main currency of the world.
As for taxing Bitcoins, I think that it would somewhat impossible to achieve, since you would need to be able to track every user, their transactions, among many other things. If the user uses a different Bitcoin address for each transaction, then it would make it even more difficult for any government to be able to collect taxes from you. Just my opinion.
