We can still hope that SBD price may move upwards and we can use some SBD from DAO to actually buy STEEM from the internal Market and burn them .

TBH, I don't really expect the external price to move far above the conversion price for any lasting time period as long as the STEEM price remains below the haircut price. The two have been tracking pretty closely ever since the Upbit delisting. You can see that pretty clearly in the two visuals I added later, at the bottom. Pure speculation on my part, though. Time will tell.

Buying STEEM and burning that would probably be more productive. That actually would reduce the current supply and virtual supply, and therefore inflation. Also, it would put buying pressure on the price of STEEM, which should might even raise the price of SBDs (despite the selling pressure) by getting the STEEM price closer to the haircut price. There are trust issues doing it that way, though. I'm not a fan of trusting any single account or team to do it.

At one point, some of the witnesses were working towards accomplishing that with a multisig mechanism. Not sure if that initiative is being reinvigorated (it might have depended on Upbit?), but I think that would be the best way to do it.