I mean in New Vegas based on your reputation with factions they would help you e.g. NCR give you an Emergency Radio, Legion give you dropboxes etc. If their is The Dark Brotherhood or Thieves Guild will they provide information for helping/leading that guild, will a Fighters Guild type provide the Men or resources at your disposal kind of thing, will there be more Guilds than Oblivion?? I just think it would be more satisfying to gain something for sticking your neck out for that faction, will they'll return the favour?

That actually sounds like a good idea, a little help, even if it's only a good advice and a show of awareness about the current events form you faction members would be great!