I remember OpenBSD working on this about 10 years ago. Also, strictly speaking transitioning with the CPU architecture is not enough -- having kernel APIs and

I remember OpenBSD working on this about 10 years ago. Also, strictly speaking transitioning with the CPU architecture is not enough -- having kernel APIs and ABIs have 64-bit time_t is not the only place it needs to change. Notably, it has to change in the filesystem too. And at that point millions of people will have on-disk structures with 32bit timestamps, so it needs to transition in a somewhat back compatible way.