serious changes

Sure but HDB doesn't work well. Worst case it has the same effect like you describe here:

I've already seen mechanisms of this type pretty much destroy a chain

a longer Bullrun that prints a lot of HDB can Inflation ruin any worth of Hive or Hive power.

And the funniest point is, they don't buy Hive, if it's cheap with money and we have a supply and demand situation, they are simply creating new Hive with their HDB and make the cycle even worse.

For that reason, I think a 2nd layer solution is probably best for testing such ideas,

I agree with the testing point, but a lock-up/loan mechanic can work there too. And if it would in a way like DAI, why we should have HDB?

HDB would be the ugly little brother that can burn Hive, but doesn't bring any value to it.

IMO, and I think I'm alone with that, we should try more new things out and copy things from others that work and already good. I know, Hive devs want always to reinvent the wheel.

Edit: We already can learn from DAI. It's not like we need to learn every lesson on Hive. And I would love a loan feature, would make so much more sense to Hold larger amounts of Hive.

Edit 2: To secure loans it can be also a 100 Day ( +- Timeframe) Average price for loans. IMO it would be super abuse save.