So if TUSD implodes, what are the implications for crvUSD? The

monetary policy logic can exclude the calculation if it deviates far enough from the other pools, so that is not a worry. But the PegKeeper has 25m debt that it will deploy that basically becomes exit liquidity. If TUSD permanently depegs, the PegKeeper can never withdraw that 25m debt

Good question (and fair question for any redeemable stablecoin). When it starts imploding - most likely it will drag crvusd price down, so that will stop pegkeeper from being filled. But it's quite a meh protection. We've got an interesting proposal where pegkeeper checks average price of all other pegkeepers and if it is lower - it skips this one. + some other things to improve. So I guess we'd want to vote some new pegkeepers in soon

EL PK will likely hit that 25M cap as LP will see a lawsuit from CRVusd over Tusd; I understand that it would not take off through the oracle mechanism, but it will leave 25M of CRVusd without colateral; as Mich says, they will look for liquidity in other LPs; These PKs that receive the supply will reduce their debt, here my first question is if the PK can burn unminted supply?

No but in the case of a stable depegging in one of the pegkeeper pools, the price aggregator could ignore that pool entirely. Even so, I imagine in the future, more fiat redeemeable stables could be paired with crvusd to spread the risk out even more so.

yes, it wouldn't be a direct depeg problem; but 25M without collateral today would represent 1/5 of the supply, it seems an interesting scenario on which to think about possibilities/solutions

Extreme scenario of course and would imply that these redeemable stables in pegkeeper pools would not be redeemable or a situation similar to what we had with USDC a while ago.

There aren't many ways out to redeem most stablecoins. I think coinbase is only place in the world for 1 for 1 USDC redemptions for retail. TUSD used to redeem in the US 1 for 1 but I think they closed that and it's never coming back. I think the chances one of these stables becoming unredeemable, even temporarily, is pretty damn high