Sufficiently low enough demand for Hive while simultaneous high demand for HBD savings can result in a net decline in demand for Hive (even accounting for the Hive burned by Hive to HBD conversions), and reaching the debt limit ahead of such an expected timeframe. I'm not saying this is a likely scenario, but it's very much possible.
My concern though is not about that happening, but that through our pursuit of "stability" for HBD interest, we train the market to expect that HBD interest is not supposed to change. There are commenters in this thread who already appear to believe that HBD interest rate is a promise not a policy, as if it were hard coded and required a hard fork to change.
HBD is only supposed to be stable in price. APR and consequently APR stability is just a means to an end in 1) bringing in capital, 2) developing the network effect and 3) helping to maintain HBD price stability. We should not spend more than we need to in the aim of achieving those things, and we do not need to add APR and investment stability as an end in and of itself.
I am not concerned that it is urgent, but in the long run, if we train the market to believe that APR stability is part of the promise of HBD, that will have been a mistake.