Lol, I wouldn't be too concerned, though. Steemit's got way too many issues to work out in their base platform to be competing with BitShares as a decentralized exchange any time soon...
I agree with this .. steem wasn't built as an exchange and building an exchange as bundle of smart contracts (as people are doing on ethereum) will not be competitive to BitShares.
Also, we already HAVE the exchange running for any asset! It will take months for steem until they can deliver smart contracting (something we don't want to have on BitShares, btw) and THEN, they can start with phase 3.