Postulation on Supreme Commander

First off this is about the single player game and be warned for I am posting spoilers. Like some other gamers, the end game videos except for the Aeon were unavailable to me. At first I thought it was because I finished the Aeon last and that I had to 'unlock' the other endings so I tried the campaign with all 3 factions again (on Hard), but this time left the UEF to last and did the Aeon first.

But I still ended up with the same blank screen with Alt-F4 as the only way out.

While I would like to engage in discussions as to the possible unit types of the 4th faction, it is perhaps of too large a scope to effectively undertake. I do agree however that it is likely to be of a bio/mystical nature with units reflecting such. But while the actual units may not be easy to predict, the storyline is perhaps more transparent.

As I have not been able to view the other two endings, I cannot postulate as effectively (I especially loved the detail behind the scanner colours posted by DeadMG) but this is my theory:

The 4th 'Faction' for the coming expansion is the Seraphim, or the progenitors/legacy of the Seraphim. This is because during the Aeon campaign, the Princess herself often wonders 'why the Seraphim gave us these gifts', once she 'Transcendes' and discovers her 'true purpose' or 'true destiny' she utters a 'NO!' hinting that she may have doomed all of humankind rather than save it.

Combine that with Brackman's observation that the Aeon do not know what marvelous technology they have. To quote 'they just put it in a temple and worship it but do not know what it can do.'. Once you realise that Brackman intergrated Seraphim technology into QAI, then QAI's response for 'Primary Objrctive Completed' becomes more obvious.

With regards to the UEF ending, besides the stealth indication, it's usually the first faction you play and thus provides more of the 'there's more to come' part of the story.

This allows for any of the 3 factions victories to allow for the explanation of the 4th.

UEF:
Destruction of the Seraphim by Xenophobes and actually using Black Sun proves to the remaining Seraphim/whoever that Humankind is a threat that cannot be ignored and must be annihilated. It helps that the UEF just quantum disintegrated a number of their own worlds and are now ripe for invasion. The stealth attack is probably to eliminate Black Sun.

Cybran:
The Seraphim tech altered QAI to 'summon' the 4th faction. The reson the 4th faction did not previously attack was because 'The Way' had not yet weakened humankind. When QAI destroyed all the Quantum Gates humanity was now isolated and could be destroyed in pockets. It is aslo probable that QAI provided valuable intel (combat data, weak locations, etc) as part of the Seraphim programming.

Aeon:
As the pawns of the Seraphim, the Aeon did exactly what the Seraphim wanted, which was to 'Cleanse' most of humankind. After all, an 'Infinite War' is not without it's cost. With their powers of precognition, the Seraphim may well have seen their demise at the hand of the humans. 'The Way' may not be so much a path for the humans but more of 'A Way Out' for the Seraphim. A thousand years bought with the sacrifice of many Seraphim and much much more human blood would have given the remnants of the Seraphim enough time (1000 years, ie: The Infinite War) to make a comeback. And as we all know, "Repensum est Canicula".