It would be possible for me to give a more nuanced take, but the upshot is: none of that shit is going to work 100%.

One may get local maxima like an unsafe bonanza, or something that introduces a custom runtime memory management discipline at the cost of performance etc. Fully equivalent C++ to Rust in full generality is mainly wishful thinking. Of course that does not mean one should not try it.

See also my other comment.

Oh, I 100% agree. The question is how much you can reduce the effort of the port/migration, and in particular the validation effort.

I've worked on projects where the core bits of code were "90%" converted by some automated tool, and in my view the overall benefit to the project timeline was probably only 20-30% because of the Amdahl's-law-type overheads of validation and bits of code not supported by the automation/conversion process. Nice, but no silver bullet.

Non-idiomatic porting also isn't super-helpful if the resulting code isn't maintainable.

As I pointed out in a sibling comment, the plan isn't for it to work. This is a job posting for a researcher at MSR to investigate what it might look like someday.