I would also like to hear what more dev heads think about whether this issue will delay the practical arrival of Cardano DEX beyond the hoped-for end of Q3 2021. I can’t recall reading any Cardano DEX funding proposal or white paper mentioning this aspect of concurrency:
It was discussed here, but not with respect to any timeframe:
My impression so far (I’m not a Plutus developer) is that the assumption of Cardano DEX by the end of September, long expected to shortly follow the Alonzo release, is therefore overly optimistic, not taking the concurrency related dev issues into account: sounding more like we might not expect it until early 2022. Of course if this turns out to be pessimistic I will be thrilled to find out why. 