One thing that keeps bugging me about post-quantum migration: we talk about swapping algorithms like it's a library update, but most systems have cryptographic assumptions baked into their wire formats, key lengths, and verification logic. The real bottleneck isn't 'which PQC algorithm wins.' It's whether your system was designed to treat cryptographic primitives as replaceable components in the first place. Cryptographic agility isn't a feature you bolt on later. It's an architectural decision you either made at the start or you're now paying the cost of not making.