"Mythos capabilities" is not some magic threshold. This is exactly the type of language that people used about GPT-4 in 2023. Today, I can run models far stronger than GPT-4 on my laptop at speeds better than GPT-4 offered.
Anthropic are quite good at coining sticky phrases like "Mythos-class models", but these are manipulative attempts to shape the discourse for business purposes and should be identified as such.