If you're worried about elliptic curve cryptography being broken, then don't store any significant wealth in Bitcoin. Just like if you're worried about your (real, physical) wallet being stolen don't hold more cash than you need to get through a couple of days of purchases.
By the way: I think an economical method for separating gold atoms from seawater will be found before elliptic curve cryptography is broken (and I think both are unlikely in the next 25 years).