What will be the future of Steem (social blockchain)?
It is really hard to say because the ecosystem keeps expanding all the time. New apps and Steem-Engine tribes keep cropping up without anyone making centralized decisions. Steem is a protocol and users, developers, app owners etc. do what they see fit with it.
I think the future is growth. Slow organic growth likely to pick up speed along the way. I suspect the social side of Steem will be dwarfed by games involving digital assets taking up an increasing share of the transaction capacity. Cryptocurrency markets go through cycles while Steem keeps chugging along and building. New tools will be developed making development easier and more productive. The blockchain fades into the background. Not all users will even have accounts of their own.
As the years go by, the content reward pool will shrink. Earning on Steem will be less about earning STEEM on content. Steem Power holders will delegate their Resource Credits to apps who need it to let their users interact with the chain. SMTs and SE-tokens will be used to monetize user experiences on various platforms allowing users to trade their tokens on open markets.
For more info on Steem, join the Steem Quora Space called The Steemian Roundup - link: Steemian Roundup