But that is just a raw representation of a pointer, what you actually pass and use as a pointer is not long values, but MemorySegments (formerly MemoryAddresses

But that is just a raw representation of a pointer, what you actually pass and use as a pointer is not long values, but MemorySegments (formerly MemoryAddresses) — so the actual size is just an implementation detail. Plus Panama won’t go stable until Valhalla, which is necessary to actually have a “long long” in the language.