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
Bitcoin price will of course soar higher as we will end up seeing investors trying to quickly put their funds where at least find a better value. However, in a case that something like this end up happening, I guess global currency power won't just shift from USD to Yuan just because of that and I really do not know how something like that would even play out.). But I think this case will never happening cause dollar will never being replaced by Yuan One thing is that other currencies will just end up stronger, but I do not really think that can cause another currency like Yuan being used as a global currency.