I also believe that it can replace in the future because the cryptocurrency today is in the mainstream and even countries are banning bitcoins because they are scared that more people will turn their focus on the cryptocurrency more than working on the corporate world.
I think many countries have not even heard about the bitcoins, so paying in bitcoins as a mode of payment is very difficult and it will take a long time to happen, but dollar is widely used and widely accepted in every country, bitcoin is new technology and dollar is traditional, bitcoin will more stronger in future but I don't think it can replace dollar worldwide. As dollar is the universal currency and many of the country use it universally even world bank gave you loan in dollar so, its very hard.