Reduce interest
As far as the numbers go, HBD can absolutely sustain the the %20 APR rate, even if we forecast the numbers of locked-up funds doubling from now. But I understand where you are coming from. You want to shift the spotlight back to HIVE.
While I understand you want to bolster the the dApp development side of the Hive to the outside world, breaking perhaps the most important bargaining chip we have to attract new users to our platform is not a good idea. You may get away with setting the APR to something around %15, but any lower than that and you lose momentum, especially as the markets are all gearing up for volatility
It's far easier to attract potential developers by incentivizing them to deposit their funds as the first step in their pathway to becoming a developer on hive, than it is by simply telling them about the great perks and benefits of developing on-chain. Hell, this is how I ended up touching any sort of code myself! I developed a plugin for PeakD when 2 years ago I joined HIVE because I loved the sleek Leofinance frontend, and wanted to try it out lol
Do you get what I'm saying? When you consider that every new user that joins hive could POTENTIALLY become a developer, that first step/bargaining chip seems so holy so as to tamper with.
Reducing Post Rewards
I don't think shifting the %10 around is a good idea, but I don't necessarily think its a bad idea as well. Keep in mind that you are gonna be giving curation services being delegated millions of HP even more power this way. With the %10 increase in inflation, who's to say people who were raking in the %20 aren't gonna delegate their stacks to these services?
I would also add that this will probably affect coin distribution negatively, where blocktrades can pass a proposal almost single-handedly. This will give much more governance power to big holders, and fuck over small holders. My 2000HP stake getting a 1% extra due to inflation and someone holding a million HP getting 1% extra due to inflation is not really the same.
And I would say there is a conflict of interest aspect as well, since Witnesses get paid in Hive. So giving more to staked hive, basically means they are paying themselves more.
This is the other thing I'm afraid of. They are gonna get even more powerful as time goes on. This also essentially punishes content creator who deservedly should receive a proper stake in governing the chain. %10 to Hive inflation simply steepens the ramp