Hopefully, the following will clarify the situation:
- King Bimbisara attained the Sotapanna stage BEFORE dying.
- The lifespans of the realms given, for example, at “31 Realms of Existence“, are the MAXIMUM possible.
- Apparently, “King Bimbisara” died several times in that deva realm and was reborn in the same realm, just a like a human can die and reborn many times in the human realm. The only difference is that there is no gandhabba state in deva realms.
– It is possible for a being in any of those realms to “die” before that time.
– If a deva with a Sakadagami stage attains the Anagami stage, then he would be reborn instantly in a brahma realm reserved for Anagamis.
– If a deva generates hateful thought towards another deva, he could be instantly reborn in a lower realm.
– Furthermore, a being in one of those realms could die at any moment due a kamma vipaka, just like humans die in early life.