Consensus Layer of Bitcoin
No direct impact: Bitcoin's consensus mechanism, which relies on SHA-256 and ECDSA, would not be directly affected by the cracking of AES, as it does not use AES for its core functions.
User's Bitcoin Wallets
Indirect impact on wallet security: Major hardware wallets (Trezor, Ledger, KeepKey) focus on secure key storage and physical device integrity rather than AES encryption. Therefore, the direct impact on these wallets would be minimal.
Bitcoin Availability for Theft
Limited direct risk: The amount of Bitcoin at risk would not directly increase due to AES being compromised, as Bitcoin addresses and keys do not rely on AES. The exposure of full public keys from address reuse poses a risk only if ECDSA is compromised. (Note that bitcoin can still be secure under cracked ECDSA, but any address which has a spent transaction output will have its private key exposed)
Bitcoin's Future Post-Event
No protocol change is necessary for AES.
Since Bitcoin’s core protocol does not depend on AES, cracking AES would not necessitate a protocol change or even a soft fork for Bitcoin’s operations. However, peripheral systems using AES may need to upgrade their security (e.g. some wallets such as Bitcoin Core).
So in summary, peripheral security measures might need reevaluation, but the primary mechanisms of Bitcoin remain secure against an AES compromise.