I really like the idea of implementing mutability control at the level of a collective as opposed to a single object. A great many transactions are multi-object.
Love the idea that a Netscape-legacy language has traction there. I hope they don’t return to their pre-Nadella practices.
Actually in Rust you have a problem where you can't express partial access to a struct at a function level. This means that you can't put some code into a separate function right now, making use of closures/iterators harder. There are attempts to fix this ([1] [2]). If borrow checking is done on collections of objects instead, the problem can be tackled more easily I think.
There's some friction there, but in practice it's easy to work around most of the time. I'm not sure extending the type system there is worth the weight.
Love the idea that a Netscape-legacy language has traction there. I hope they don’t return to their pre-Nadella practices.