Obviously during infinites campaign the endless are referenced quite a bit. A lot of community members are speculating that it’s the flood. That would be cool but let’s think about it for a second, the flood can still die, granted it’s a plague of sorts and in some ways can’t be stopped but can be prevented. But you know what can’t??? prometheans!!! In lore, prometheans are infinitely reincarnated and/or resurrected due to the permanent genetic digital imprint of their soul of sorts, and will always be “endless” in supply of their life, firepower, etc. They are immortal, while their bodies may be unkillable They’ll just come back stronger than before. The composer for example from halo 4. It incinerated be very one’s bodies but had taken and compacted their souls into a genetic/digital imprint and it will forever be implemented into an empty crawler, knight, soldier, or any other empty shell of a body it can control. But once that body is destroyed the soul moves to a different more intact body. So in turn, They are endless. life, death, repeat.
So all in all, I personally speculate prometheans are going to be returning. Not flood. There are so many signs pointing to the prometheans instead of the flood.
Post your personal thoughts in the reply thread! Thanks!