If the dollar falls I think there will be only one thing can happen with BTC is Bitcoin price will go to the moon 
). But I think this case will never happening cause dollar will never being replaced by Yuan
). But I think this case will never happening cause dollar will never being replaced by Yuan Yes it is true. Usd is never changed by Yuan. Yuan is not really accepted in most country.
But if USD fall then the time for cryptocurrency to grow more and more.