Many thanks for starting this thread @wouter. I will only make one point for now.
I believe that there’s a warning sign that’s being ignored right now but might come back to haunt us in a few months. In a bull market, DAI supply should easily outstrip demand resulting in a DAI that is below peg. The fact that this is not happening right now has resulted in the PSM filling up with USDC. This is a warning sign that the upcoming bear market will result in one of the following
PSM fills up extremely rapidly with USDC forcing the debt ceiling to rise by orders of magnitude over what it is now or
PSM debt ceiling is hit and DAI goes significantly above peg.
When ETH crashes, DAI demand will go through the roof and vaults will close choking off supply. I have some mitigating actions (however, none are even close to sufficient in my opinion)
We need immediate action to get the USDC out of the PSM. The tout fee should be set to zero. There might be some hope that DAI drops below peg as ETH continues its run and every opportunity to remove USDC from the PSM should be taken.
Set the surplus buffer to a much larger amount e.g. 10% of outstanding DAI. This should be thought of as strategic reserves of DAI, much like the US does with oil. During the bear market, outstanding DAI will decrease and the surplus buffer will then release DAI into the market. This would soften the supply crunch a little bit. The 10% number is just an example but I think the exact number can be worked out with some simulations of ETH price.