Following Dharma’s lead, I believe that all stable-coins should have their interest rate model updated to match. DAI has already been updated to the latest and greatest interest rate model but USDC and USDT lag behind.
As USDC is a legacy cToken, upgrading the interest rate model for it will require a new contract, but USDT can have a new interest rate model using the JumpRateModelV2 built by Dharma. I propose setting USDT interest rate model to a new JumpRateModelV2 deployed with the same parameters as the current DAI interest rate model: base rate of 0%, 4% at kink, kink at 80% utilization, and 25% at 100% utilization.
Update: Interest rate model deployed here.