I'm personally more worried about flaws in the quantum-safe crypto schemes than in RSA, which is based on the age-old factorization problem of prime numbers.

They can harvest all they want, but if no one ever invents a usable, practical and scalable quantum processor all this will be moot.

HNDL can be worth it without the "threat" of quantum computing; for instance we see currently a lot of interest in AI-assisted math, and maybe it could lead to a breakthrough that affect crypto algorithms that are currently considered safe.

Therefore it seems weird to use QC as a benchmark. Rather, if your communications being decrypted in the future is unacceptable, then the logical conclusion is that you must not transmit it in such a way that a third party can intercept it.

Admittedly, it is inconvenient or even impractical, so people do accept the risk anyway without admitting it. They are sweeping the issue under the carpet of supposedly QC-proof crypto - because new quantum algorithms can be discovered too.

What are the odds that a new QS crypto scheme has a fatal flaw or is otherwise intentionally backdoored?

Amping everyone up with fears over quantum breaking classical seems like a fantastic way to get another round of vulnerabilities injected into everyone's infrastructure.