This might not work, but how about this as an idea and I don't know if it helps stabilize HBD.
Use the savings wallet as a staking point like a defi pool, but it attracts Hive as an automatic percentage of curation as if it is active (for example 50%). This would give it a return of ~10% A year in Hive, less than curation, but far better than a bank. Can this pool of Hive be then used to further stabilize HBD?
I think this would may also create some market scarcity and push the price of Hive up, as it gives a bit more passive use case to holding Hive on chain, rather than on exchange.
NB: I have no idea how to stabilize a token :D
I definitely agree with providing more rewards for locking up capital (including HBD) in Hive. There was already intended to be a 10% interest for merely holding HBD, perhaps a relatively simple change would be to have two interest rates, a lower one for unlocked HBD and a higher one for locked HBD.
I think it might give a very good use case to the savings wallets and incentive to hold tokens. Bringing back for example 100M tokens from the exchanges for a 10% return would still have additional benefit for active stake, as it would create a driving price and make earning on chain more lucrative. Eventually, some kind of equilibrium would be found I assume.
The model that a number of stakeholders have discussed is to just have the interest rate for liquid HBD be zero and if you lock it up in savings (effectively 3 day staking), you get the specified interest rate (currently 3%, but could be higher, and could be higher still if it weren't paid for all HBD, only locked HBD). I think that is sufficient for a next step without needing the complexity of multiple interest rates. It serves the purpose of giving a reward for buying and holding, and saves some cost paying interest on liquid HBD for people not intending to hold for a significant period (or clueless) who don't care about that interest.
One could also imagine something more complex, with multiple staking periods and interest rates and such, but let's not go overboard dealing with an asset circulating 6 million tokens currently. Small steps, maybe bigger ones later.