As I see it, we have two options with a dynamic APR:

• time lockups (bonds?), when the APR is based on the period you are willing to lock it (3% for a month, 5% for two, 10% for a year, 20% for two...or similar)
• semidinamic APR, where we se the APR for a period (month or quartal) based on the hive debt .... because the debt and the haircut is the ultimate ruler of the system, example (debt is bellow 10%, we set a 20% APR) debt between 10% and 20%, a 10% APR, debt above 20%, 0% APR ... this again as an example numbers), we can even have a slider from 0% to 20% for each change in the debt.