Anything based on RSA, factoring primes, will be vulnerable. There are lots of forms of encryption which no quantum algorithm is known to process faster -- I believe elliptic key crypto is one. I don't know whether any cryptocurrency uses such alternative encryption schemes.

Sorry, factoring into primes. Factoring primes is easy. I can factor a million-digit prime myself by hand.

Quantum Computers solve ECDLP just as easily as factoring.

That seems exceedingly unlikely. I think it's more likely someone finds an efficient classical ECDLP (Elliptic Curve Discrete Log Problem) solver in 5 years...

On what basis do you think that the ECDLP will be solved in polynomial time in a classical context?

I would expect we will more likely have an error-correcting quantum machine sooner than the aforementioned. Given the pace Google et al are making.

We already have a quantum approach to solved ECC over finite fields, Shor's.

I don't think it will. But having quantum computers able to crack 256-bit ECDLP in only 5 years seems even more far fetched.