Vague sketch: imagine if we had scoped panic hooks, unhooked via RAII. So, for use cases that today use unwinding for cleanup (e.g. "switch the terminal back out of curses mode"), you do that cleanup in a panic hook instead.
The hard use case to handle without unwinding is an HTTP server that wants to allow for panics in a request handler without panicking the entire process. Unwinding is a janky way to handle that, and creates issues in code that doesn't expect unwinding (e.g. half-modified states), and poisoning in particular seems likely to cascade and bring down other parts of the process anyway if some needed resource gets poisoned. But we need a reasonable alternative to propose for that use case, in order to seriously evaluate eliminating unwinding.
The hard use case to handle without unwinding is an HTTP server that wants to allow for panics in a request handler without panicking the entire process. Unwinding is a janky way to handle that, and creates issues in code that doesn't expect unwinding (e.g. half-modified states), and poisoning in particular seems likely to cascade and bring down other parts of the process anyway if some needed resource gets poisoned. But we need a reasonable alternative to propose for that use case, in order to seriously evaluate eliminating unwinding.