Encrypted traffic can be recorded now and decrypted whenever the capability arrives. That makes the relevant question not when a cryptographically relevant machine exists, but how long the data you are sending today has to stay secret - and for most commercially sensitive traffic the answer is longer than any credible timeline. This is harvest now, decrypt later, and it is why the migration deadline is behind us rather than ahead.
The standards are not speculative either. National standards bodies have published lattice-based key establishment and signature schemes, and the migration guidance that goes with them, which means the engineering decision today is when to adopt rather than what to adopt.