It's definitely not true today: for example, there are no NIST standards (and I'm not sure about standards from other governments) for quantum-resistant key exchange. Several such systems have been developed, and NIST has even chosen one to standardize, but they aren't standardized or widely deployed yet.
But I expect that in 5-10 years, most security systems designed by competent professionals (up-to-date OS security services, TLS servers, SSH servers, VPN, firmware update systems etc) will have post-quantum crypto enabled by default. And I expect it will take longer than that to build a QC that can break classical crypto.
More likely it will play out like the SHA-1 break: all professional security engineers should have switched off SHA-1 (at least for unkeyed hashing) years before any collision was found, and users who apply security patches should therefore by mostly up to date, but I'm sure some are still using the older crypto.
The list of things that have to be encrypted 30 years from now is very, very small. I doubt any (many?) people here have contact with any of it. I don't understand your analogy at all, sorry.
The message I sent to my girlfriend last night. In 30 years, when I am running for president, that email/text/signal message might come back to haunt me should anyone be able to decrypt the archived/encrypted copies held by state agencies.
Anything that is private today is private for a reason. That reason doesn't automatically disappear over time.
This is indistinguishable from hoarder logic. Such things straight up don't matter on the scale of decades. The US DOJ has a policy of automatic declassification after 25 years.
You do realize that because of #metoo, claims and evidence of people's actions 30, 40 years ago are being judged in the court of public opinion, if not in actual courts?
I don't think you've been paying attention to the news.
Also the US government isn't a great example. JFK was assassinated in 1963 and all records surrounding that still haven't been released.
The idea that people don't care about secrets across the span of decades is utterly wrong.
How does encryption impact #metoo? The person waking the accusation would have a decrypted version of the message and even if they didn't they could accuse without proof.
This forum gets more and more detached from reality every day.