I believe moving liquidity incentives from iUSD/Ada pairs to iUSD/USDM, iUSD/DJED, or other stable pairs would help to maintain the peg.
Right now when the price of ADA falls their are two downward pressures on the price of iUSD in dollar terms.
1. price of iUSD also falls automatically due to almost all trading liquidity being paired with ADA.
2. People are creating and selling iUSD to create leverage if the price of ADA goes back up.
If more iUSD liquidity was tied to other stables then this would decrease the pressure of the first mechanism. I believe moving the incentives would cause a large amount of the current liquidity to move into stable pairs as liquidity providers chase the enhanced yields.
Unfortunately there is currently no easy way to apply this formula to the iBTC and iETH tokens because there are no other better pegged versions of these asset on Cardona with sufficient liquidity.