I think in the year 2100 the price of bitcoin would rise upto 1 million dollars.each and every country would adopt bitcoins as their currency and there would be only one currency in the world that would be only bitcoins.i think that at that place 2100 there would be lot of black market that we have to take care of .
It would be happened only when bitcoin alive till 2100, than off course bitcoin might be cross 1 million USD. But in my point of view, may be some other crypto currency could be come just like bitcoin, than bitcoin has a comparison, in this way, bitcoin's users take turn to other popular crypto currency.
So many other reason also here and we should avoid to predict, and see now bitcoin is in the top and give us benefits and earning, now we are happy with bitcoin, So it is good for all of us.