So far a Rust rewrite's success rate directly, probably super linearly, correlates with the presence of a good, well designed test suite. This is why Bun's rewrite and others are successful. I anticipate that this will be true for the 37Signals rewrites.
I want to learn a couple of things once they are done:
1. Once the test suite assistance is over, how do features get built in their backends and continue to maintain the same quality. LLM test writing is a bit trickier as it often favors what Randy Coulman called tautological tests back in the day. It takes a lot of work to get them not to do this, so I am guessing folks at 37Signals will read at least this part. I can't imagine zero Rust read at all.
2. Over the years they had a few innovations in their domain design, ones that Rails made easier to do, for instance their delegated type pattern. Will Rust replicate this, and how would one know without reading it, or perhaps it does not matter? Furthermore, how do newer patterns emerge? and how does our arsenal of better abstractions keep growing?
I don't have the answers but I am glad there is a chance we can learn said answers.