One of the main selling points of Steem Power was that it could be used to give posts more visibility in the "Trending" page.
"Trending" is now just a tab among many, next to the new"Promoted" tab . It is not even the default tab anymore .
Steem Power for promoting content is now a very unattractive investment and SBD has replaced it in that regard as it is way more cost/effective (safer investment also) for promoting content than investing in SteemPower.
I doubt an increased demand for SBD alone will be enough to prop up Steem. It might be helpful if at least the @null's profits were redistributed to powered up SteemPower holders as some sort of dividend.
As it stands Stem Power serves too little of a purpose anymore. It may still be useful for curation bots but for the average user/investor it is becoming difficult to answer the question "why should I buy Steem?"