I'll agree that, post-chaos theory, the mathematical aspect of Foundation is unconvincing.
However, I'm not sure that it would not have qualified as hard SF at the time it was written.
Larry Niven was famously burnt by this once - he wrote a story set on Mercury which included accurate science when he wrote it only to have the accepted scientific position change due to new information between submission and publication.
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However, I'm not sure that it would not have qualified as hard SF at the time it was written.
Larry Niven was famously burnt by this once - he wrote a story set on Mercury which included accurate science when he wrote it only to have the accepted scientific position change due to new information between submission and publication.