I think most of the DAPPS will go on Ethereum Blockchain b/c that's what it is designed to do. For Social Media Steemit is the place. The Steemit dollar peg is very interesting for remittance and store of value. Its too early to tell what we happen. One thing for sure no Steemit is booming with life, considering its just a month old!
Steem has different infrastructure but it is faster than Ethereum, which is key component for Dapps.
Well, same goes for eth, not mature enough. I do agree though, it promised to be or designed to be for dapps but proving that, is another story, the best thing happened in Ethereum is DAO hack.