I believe creating more internal demand for SBD can help ease the sell pressure a bit. The post promotion is a good start, though I feel it needs some tweaking so that promoted posts are viewable in a way that doesn't need the Steemit user to click on the promoted tab.

In chat it's been discussed that avatars and blog banner images are untapped resources. Because of the ad-free model of Steemit (so far), avatar and banner additions or changes could be restricted to those who pay SBD for them. This is not unprecedented. I know of community-supported forums that charge money to change avatars.

An avatar is a valuable way of distinguishing one's own account, comments, and posts. I think Steemit could charge a decent premium for an avatar or avatar change. Something like 20-50 SBD perhaps. It may sound like a lot but it's a valuable commodity and would last until changed.