I suspect the best case scenario is a "Stone soup". https://en.wikipedia.org/wiki/Stone_Soup
The fantasy is enough to get engagement and once you have engagement you can persuade people to do a "little" extra work to get the full benefits. My mother won't buy the product for $5, but if you tell her that it costs $10 but they're 2-for-1 today, she's going to buy that and feel like she got a bargain.
In terms of actually solving the problem well, it's not even captured in these hypothetical regulatory requirements. What you actually want is a safety culture, Rust has one, C++ does not, and no technology will change that. From what I can tell nobody at WG21 wants that to change anyway.
> What you actually want is a safety culture, Rust has one
Rust has a safety culture because it involves requirements for Safe Rust that preserve safety while also playing well with modularity and iterative development. If "Safe C++" can enforce similar requirements, we can expect that a safety culture can be sustained there as well.
The technology does not gift you associated culture, and it's worth knowing that even far outside this business because it applies everywhere.
Yes a technology can be enabling, but, it isn't enough to inculcate the desired culture, that has to come from somewhere else. You can't "sustain" something which does not exist.
Actually WG21 ("The C++ Language Committee") illustrates this well in another way. When WG21 was created it was after the Mother Of All Demos, and so after video conferencing exists as an idea, but to be fair to them it was not really practical at the scale needed for WG21 processes at that time. When C++ 98 shipped it was just about practical, although most ordinary people would have needed to travel to some place with appropriate equipment. By this point the IETF is routinely but not yet universally using such technology.
By the time C++ 11 shipped, I have an ordinary job where I worked full time from home, travelling to a physical location only once or twice per month because video conferencing is now such a mudane and ordinary capability as to go unremarked.
Only since the COVID-19 pandemic has WG21 finally adopted the option for attendance without flying around the world several times per year. The technology to do this had existed for decades, but the culture did not exist.
If you have access to the WG21 meeting minutes, it appears the safety discussions of the last meeting were quite entertaining.