You gotta do some pretty crazy shit to get banned from Yahoo, in my opinion.
I look at this change as a spam clean up. They cut off sub domains, with a focus to clean up the listings since so many people were link spamming with ref codes across several sub domains.
Being so it's safe to assume that they would devalue the listings found from the sub domains that didn't make the cut. The domain wasn't banned just dropped until it's found through a root domain or allowed sub domain.
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