And let's not be obtuse, some of those subsystem maintainers are staunchly opposed, so "it's up to them" is obviously an indirect way of saying "no rust". I don't blame those maintainers for balking at a whole new very different language, but Torvalds has a choice of telling them either "suck it up, buttercup" or "I hear you; rust is gone". Instead, he's just letting things fester.