I don't think so, maybe the the goverment won't agree that bitcoin will replace dollar because first of all bitcoin was not created by the government. We can't say when bitcoin can consider a real money because we can only earn it in the internet. Maybe one day bitcoin can replace dollar someday.
yes it is not possible to replace the dollar on a whole. dollar/fiat currency which is directly from the government side is much trusted and valued. it is very handy to use as whatever you need you dont need to convert anything you just have to walk in to the shop and get it whereas in btc it is not the case and even if it become very much popular still there will be places where btc will not be valid because it is crypto currency not a government authorized one. just try to explain one thing btc will skyrocket but dollar is required at any cost.
I wouldn't say "at any cost" because there might be a point in time when the price of things will be based in bitcoins instead of fiat. Since the price of bitcoin has skyrocketed, bitcoin is already accepted by the mainstream. The price is a clear sign that huge businesses are already in the bitcoin thing.
Same as fiat, even if bitcoin gets popular, it might not be accepted at some places. USD is a very famous currency because the United States is famous and have been a dominant country for a long time. Try using your USD in Korea or in China or literally in any other place, you will still have to convert that first to their local currency. Maybe large establishments abroad will accept that but I doubt a small scale market will accept that.