One of my favorite things about End of Nations is that, if implemented as Petroglyph and Trion were originally envisioning, it would be not just an RTS/tactics game, but a platform on which to deliver additional content over time. New units, heroes, mods, skins and even maps (we saw how easy it was for them to turn maps on and off without requiring a game update) over time.
But, it'd also be relatively easy (depending on how the meta ends up working) for them to add new factions. Personally, I hope to see the first new faction enter the game between 12 and 18 months after release (again, assuming Trion keeps supporting and developing for EON after they launch it) and for them to release a total of 3-5 factions (I feel like 6 or more would be excessive though I'd be happy to be proven wrong)
According to Faction Calculus on TVTropes (http://tvtropes.org/pmwiki/pmwiki.ph...actionCalculus) the 3rd faction would probably end up being either the Powerhouse or the Balanced (I feel that the Shadow Revolution is still placed as the Subversives in this case). Either way, I look to the Order of Nations itself for a good initial 3rd faction.
Honestly, if the Order were added, you'd probably still be able to do existing missions without having to rewrite the campaign much. Player Order units could be retconned in as something of a "secret police" or "special forces" branch of the Order, who are tasked with "testing" or "winnowing" the weak of their own government at the same time as controlling and corralling the efforts of their guerilla fighter enemies. Player Order actions against NPC Order could be seen as necessary towards their larger goal, and NPC order missions like Last Stand or even Hold the Line could be explained as the NPC order commander confusing Player Order forces with the SR.
Indeed, the Player Order could be expected to do weird things like save civilians from the larger Order... Imagine if they're trying to find LF or SR bases, and have "planted agents amongst the refugees" - holding their brethren off helps them get their agents under cover. There could even be alliances between Player Order commanders and LF/SR commanders - they could claim to be defectors, working towards nefarious and clandestine ends.
Anyways, I think seeing players being able to join the Order and fight for them would be awesome.
I also think that there could be a post-apoc cyberpunk faction. Think the player-made Forgotten from the C&C games. They would be free peoples, living under the radar of the LF/SR/Order. Think the town from the End of Nations comics - they'd be homesteaders, living in bombed out cities and deep in the wilderness, fighting in small numbers and with outdated scrapped together technology against the overwhelming tech and force of the 3 major factions. I could see suicide units, Ewok-on-Endor style dumb traps, GLA-style Scap tanks that get stronger as they kill enemies and acquire their weapons (looting a Shiva cannon on the battlefield BOO YA)
What about you all? Thoughts?