To pick on a small part of your comment: Do any theoretical computer scientists seriously worry that a proof that P=NP would threaten cryptography? It's not like a proof would suddenly make an i7 able to factor huge numbers in polynomial time. Also, while all polynomial-time algorithms are considered "tractable" in theoretical CS, that doesn't mean that they're all practical on current hardware (nor does it claim to mean that).
I suppose a proof that P=NP would still technically threaten cryptography, because if you assume that computer hardware performance increases polynomially with time you must concede that any given crypto technique will become practical to break after some amount of time.
I suppose a proof that P=NP would still technically threaten cryptography, because if you assume that computer hardware performance increases polynomially with time you must concede that any given crypto technique will become practical to break after some amount of time.