It's only a matter of time before the Linux kernel itself is rewritten in Rust. Or, more likely, a Rust-based replacement is written.
I am fully Team Rust for core infrastructure, but I am curious how many security blunders in the kernel are memory errors vs bad security architecture.
If starting over from scratch could you ignore most architectures, drivers, etc and support current hardware ... also yes.
A new OS could skip 32 bit mode, alpha, mips, itanium, loongarch, 68k, pa-risc, powerpc, s390, superH, sparc, parallel ports, serial ports, supporting zillions of PCI/PCIe cards that you can't buy any more, messing around with archaic 16 bit bootloaders, etc.