It depends on witnesses getting on board with this kind of policy. If they don't reduce during bull market then it doesn't work. In the long run I think it should be made a stakeholder vote (based on stake-adjusted median). It's economic/monetary policy and stakeholders are the ones paying the cost of being diluted.
TBH I'd rather stick with 15% now and gradually reduce once Hive price starts to recover.
Burning the DHF would end the hemorrhage of Hive onto the market from that source, and that would strongly assist the restoration of token price.
It would be a strong signal of commitment to fiscal prudence.
However, I honestly think the market isn't really watching for signals relating to Hive governance decisions. Rather, the price goes up or down primarily due to broader sentiment, with token supply having an effect as the rubber hits the road (ie. more supply directly landing on the market).