Shouldn't past datetimes be stored as nanoseconds offsets from EPOCH and future datetimes be stored as local time? In this way, we can tell the exact time some

Shouldn't past datetimes be stored as nanoseconds offsets from EPOCH and future datetimes be stored as local time? In this way, we can tell the exact time something happened in the past, no matter how timezones/DST changes, but we can also have future events stored according to people's expectations.