Check his comment to a poster that asked the same thing (why would P != NP change anything):

    P≠NP is exactly the ‘expected’ answer! But proving that
    expected answer has been the central goal of the field 
    for 40 years—not so much (in my opinion) because the 
    answer itself is in serious doubt, as because of how much 
    will need to be learned about computation on the way to 
    the proof. If P≠NP is proved, then to whatever extent 
    theoretical computer science continues to exist at all, 
    it will have a very different character.