Probably never for package based distros. I could see it happening for image based distros, where systemd is slowly but surely providing all the building blocks for. It has had the option for `NoNewPrivileges=` in the `system.conf` since v239, so it isn't exactly difficult to disable for the entire system.
Though you'd be surprised how many binaries are suid binaries while they probably shouldn't be (passwd, mount, groupmems, ...), though alot can also work without being suid just more resticted in what they can do.