I agree with others that Mashable is deteriorating in quality. However the bulk of their visitors, I bet don't come from "devoted" followers, but rather from search engines, I would venture around 75-80%. They're like a content farm disguised as a quality blog network. They put out 10-20 pages a day, for 4-5 years, and each page gets like what? 20 links, 20 likes, 20 +1's? That all adds up to high search engine rankings. At this point it doesn't matter if Mashable jumps the shark - they can just keep on putting on mediocre content, and it'll still rank based on their brand and authority.

I don't know if CNN knows that's what they're buying - they probably think Mashable has lots of "fans". They do, but it's not that valuable.. definitely not 200 million valuable. If Google gave them a site-wide penalty, their traffic would plummet overnight.