If the majority of the witnesses upgrade by that date the hard fork will go into effect
According to this post, "It takes 2/3 majority to change the software rules behind Steem. So everyone can rest assured that any change to the protocol will be thoroughly vetted and supported"
Is it a majority, or a 2/3 majority, and why?
According to the code, a hard fork will only happen/execute if
15/21 = 71.4%
).