Dear Jdcv97,
Thanks for sharing your concerns.
I firmly believe that a quantum computer powerful enough to break the public key cryptography currently used by ICP will exist one day—and that day might be sooner than we think, though not within the next five years. The chip that Google has publicized is still many orders of magnitude away from meeting the necessary requirements. This is because many physical qubits are needed to implement a single logical qubit, due to the necessity of error correction. Additionally, as quantum computers grow larger, even more error correction will be required to address interference not only between qubits themselves but also with their surrounding environment.
The algorithms in question used by ICP are all discrete logarithm signature schemes (BLS, ECDSA, EdDSA, and Schnorr) and a discrete logarithms based VRF (BLS).
At Dfinity, we are fortunate to have team members with significant expertise in post-quantum cryptography. For example, I founded the post-quantum group at IBM Research Zurich, which won the NIST competition.
Notably, ICP was designed with the flexibility to replace cryptographic schemes easily if needed (this is often called crypto agility). The most significant inconvenience when swapping the cryptographic algorithms will be that the public key of the Internet Computer will change (having said that, changing public keys is a normal procedure in key management).
We are, and have always been, closely monitoring the situation and will propose replacements for these algorithms to the NNS at the appropriate time.