I have been meaning to ask this question for a long time. Is it possible that the Gravemind is still kicking? To me i say he is why he is such a huge presence in the games and with being a big boss monster normally would have a big scene of said big boss monster dieing.
No, it’s quite impossible. However, that doesn’t mean that another Gravemind will exist. A Gravemind usually comes around at a certain stage of Flood evolution. In the first game, Keyes among with the others in that huge blob thing were going to be part of a pre-Gravemind.
Nothing that didn’t make it through the Portal survived Halo’s activation.
The Flood, however, could still exist, there are likely still some at Delta Halo, and on Threshold. And it is likely more Flood are kept on the other 5 Halo rings, and some of the Shield Worlds. And where there are Flood, a Gravemind can be born.
Though a new Gravemind, if including the Flood from Delta Halo, would likely retain all knowledge the Gravemind had before he left for Earth.
I doubt the halo2/3 gravemind is alive but there could be more, i mean if both the halos from CE and 2 had flood its most likely all of them have.