[Ajedi32]

A practical quantum computer would be capable of breaking almost all modern public key cryptography.

There's an entire field of research dedicated to figuring out what we'll replace those algorithms with if quantum computing does become practical on a significant scale: https://en.wikipedia.org/wiki/Post-quantum_cryptography

[umanwizard]

Specter and Meltdown have nothing to do with cryptography

[has2k1]

Most side-channel attacks have mainly been a threat to the implementation of cryptographic systems and algorithms. Now Specter and Meltdown have brought that concern to all systems.

The gist of the parent post is, create complex systems and these things will bite.