This seems even more convincing to me when taken in context, especially how it says that "we" are witness to the aftermath and that the character yet exists as one ("I" speak to you of my intent.) My theory follows as thus: the forerunners died willingly yet spearing the humans. Therefore they thought that it wouldn't be the end.THIS IS MY FINAL ENTRY, AND I AM LEFT WITH ONE HOPE
With fate we escaped, and fate we may relive.
I almost convinced myself that no one was listening; that the waves of the past would roll through once again.
After all, here we are, witness to the aftermath.
I speak to you of my intent...
Here's the sum. The forerunners planned to escape the flood and leave mankind to do the dirty work of letting them out in a few hundred thousand years when the flood were completely died out. They planned to do this by invoking one of the halos loopholes: storing their bodies as sperm and egg cells and keeping the last of the race as a collective of AI minds inside the Ark until they could get their bodies (the result: MB.) This is how the forerunners survived, they were not life when the halos activated so they wouldn't get wiped out and they just have to wait until mankind develops and lets them out when the flood are gone. Simple: there was no flaw in the plan until the covenant showed up and started the war right on top of their Ark.They, and all other sentient life, died, as planned.: 343GS speaking of the forerunners
After all, here we are, witness to the aftermath.: A forerunner
This is how the Ark truly saves you. The humans went unnoticed by the flood and since the forerunners (too large in number to hide with the humans) were gone Earth was safe.
(More to come, until then check out my other post viewtopic.php?f=13&t=576 it explains some gaps)