Steemit the company and Steem the protocol are two different things just like Coinbase the company and Bitcoin the protocol are two different things.

Its unlikely Reddit would buy Steemit anytime soon, but more likely they would adopt the protocol. With 250M MAUs, they have a huge network effect advantage, though they are missing the ability to empower and reward users. That's something that utilizing the Steem protocol can offer them and they can do that for free (all it would take is dev work).