if anything were to crack, like maybe because of the advent of quantum computers, I suspect the first thing to crack is the private key in the wallet, since a powerfull enough quantum computer with enough Qbits could crack the privates keyes using Shor's algorithm.
All the wallets use the exact same public/private key system, so all the coins would be at risk IMHO
if ecdsa over SHA-256 could be cracked last thing to worry about would be your wallets as a lot of systems use this hence why it is in the OpenSSL library
but it is a weakness and a valid point public/private key systems are a weak link in most online and p2p systems
To solve issues like this I did research things like MQQ (multivariate quadratic quasigroups) which I quite like and can be used in a MPKC (multivariate public key cryptosystem)
this paper gives a good balanced view of MQQ and its use as a MPKC
http://www-polsys.lip6.fr/~jcf/Papers/CANS2010.pdf
this is also quite good
http://www.mini.pw.edu.pl/aaa80/Presentations/Talks/Christov.pdf
this could be used to replace the public/private key systems if a problem was found
also you could see the use of a SAT solver for the POW/POS mining but have yet to see more than just a test case on Bitcoin, if a true SAT Solver on the GPU came out for Bitcoin the difficulty system for POW would not work correctly and POS is based on POW so that also would have issues
http://jheusser.github.io/2013/02/03/satcoin.html
why? because the higher difficulty would only help to limit the potential inputs of the search