Presumably each faction also has a backstory and goals, which the player fights for as well as for their own loot and gear and the overarching goal of saving humanity. Perhaps we see a Borderlands-type interaction between the factions and the players; while allied factions will be proactively generous with assistance, others will be more antagonistic when they can afford to but grudgingly cooperate when cornered by Cabal. It would also be interesting to see how factions affect the storyline of future DLC/expansion packs/"titles". Like say Dead Orbit becomes really big, to the point where two or three of the other factions truce, ally, and/or merge with each other in the interest of competing with/negating the sheer bulk of Dead Orbit. Or at some point FWC takes over Mars, which is against the interests of Seven Seraphs and Osiris but Dead Orbit and New Monarchy don't really care, so there's a tug-of-war of convincing uncommitted players/factions to fight for them which in the next DLC not only becomes canonized but escalated with New Monarchy joining FWC and Dead Orbit's like "OH I [I]KNOW[/I] YOU JUST DID NOT" but they still don't care about 7S or Osiris, so it's like a three or four way battle, and oh lookit that a Hive invasion? Who's going to fight together to survive and who's going to stab each other in the back? So many possibilities, not nearly enough information revealed about any of this and that needs to be fixed. [i]Are we there yet?[/i]

Perhaps if you join Dead Orbit, for example, you may get a small bonus in ship to ship combat, like the name suggests.