Guarantees for `VkPhysicalDevice` validity?

The spec currently says this:
> `VkPhysicalDevice` objects **cannot** be explicitly destroyed. Instead, they are implicitly destroyed when the `VkInstance` object they are retrieved from is destroyed.

This could be interpreted as providing certain guarantees for the validity of `VkPhysicalDevice` handles, but I'm not sure. Could the truth of these statements be clarified?
- Once a handle has been returned by an enumeration, it's always valid as long as the instance exists.
- A lost device that is re-established is given back its old handle the next time physical devices are enumerated.
- A new device never re-uses the handle of a previously lost device, but is always given a fresh handle.