"Current encryption will become obsolete" - only asymmetric crypto. Symmetric crypto, as well as hashes aren't affected (at least not much, you might want to double key sizes but you don't need fundamental changes.)
"Post-quantum key sizes are larger" - that depends. Basically, the algorithms are less efficient than conventional asymmetric algorithms, but there are quite a few different options out there with different inefficiencies. For example, SLH-DSA has tiny keys, but the signatures are huge and making them is very slow.
This is only news for the kind of people who refer to large language models as "AI".
Unfortunately, that's quite a lot of people.
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If someone is researching AGI, there's a good chance that "whatever the hell they want" is for everyone to have access to AGI, that's the most obvious motivation for doing so. You are confusing intelligence with psychopathy. I suppose it comes from living in a society in which the media-political establishment worships obscenely rich psychopaths.
In any case, I don't know why you're so convinced that AGI would be smarter than human intelligence. I would expect the first one to be pretty basic, that's how technology normally goes.
"It's my cookie file and if I come up with something that's lame and I like it, it goes in." -- karl (Karl Lehenbauer)