Yeah this is quite a big deal. If P != NP (what we suspect, and hope) then it effectively functions as a undeniable and rationalistic higher power that us mere mortals can use to our advantage like gravity. This points to the possibility that they *might* actually be equivalent, and if that's the case then cryptography (except perhaps quantum cryptography) effectively dies all at once. There are smaller potential degrees of impact as well, others much more intelligent and well read than me on these matters are seriously concerned that we might lose public key crypto and secure key exchange, which would would be nearly as catastrophic. If cryptography dies, then the landscape of information/computer security changes instantly and we become completely dependent upon secure logic and machine isolation.