For most applications, 500 years and nanosecond granularity is not "problematic". The handful that need greater range or precision (or unlikely, both) can roll their own data structures or use a specialised one rather than needing to cater for that in the default.
You can always use floating point representations. It will give you great range and great precision, though not both at the same time (you can't refer to a specific picosecond on a specific day 100,000 years from now).
You can always use floating point representations. It will give you great range and great precision, though not both at the same time (you can't refer to a specific picosecond on a specific day 100,000 years from now).