If a billion people gets involved with the market then it might be a good thing because that would mean that there will be a billion times more demand for the coins in the market compared to what it holds now. The market will then be at a better place than it is now.
Yes but with the growing demand of coins and new projects coming out everyday, Bitcoin could one day be replaced by something bigger and better! I do not ever believe it will crash but I do believe one day it may be a less chosen currency!