One of the solutions (which may be implemented in future: see comment section of the blog) to improve Steem's price is to restrict Steem's inflation for worker proposals, witnesses (50-100 instead of 20), and PoS stake. APR for hodling SP can be increased to 4% from current 2%.
Rewarding contents should be done with SMTs/Scots other than Steem. STINC or @busy, @steempeak can launch their own token. Then the success of the token will be depend the the company or founders behind. DApp founders can play with their own algorithms for reward pool, burning policy, buyback with Ad profit or whatever they think it will be appropriate.
Steem will be only required for transactions (RC), RC requirements for onboarding new users and speculation.
Even current inflation will be sustainable if Steem can onboard 10 or 100 million users through its plethora of DApps. Active users will need SP to transact. They may not earn Steem but other DApp tokens.