We have started looking at several of the most popular projects to evaluate their reliance on DSA, with DEXes high up on that list. However, most of the DEXes we have looked at so far use mechanisms of off-chain order matching and only do on-chain settlement (e.g. IDEX and 0x). The settlements there are either already SSA or could be easily adapted, given that the counterparties are already known at the time of transaction creation.
Additionally, Uniswap as the most popular DEX uses a one-sided model, where trades happen directly with the Uniswap exchange contracts - so no problem there either.
We will continue looking at additional Eth1 projects to see whether there are any more fundamental SSA issues. It is important to note however that even for complex use cases like on-chain order matching there could be SSA workarounds (see e.g. this old post by Vitalik, specifically the “On-chain order books” section).
We are also developing tooling around SSA contract development, hoping to demonstrate how the move to SSA would only have a minimal impact for contract developers.
We will likely have further results of our SSA research to share later on, which I will then make sure to link here.