Whadda ya think.

Dont count on it.

like how large?

You know maybe some loyalists to the empire are escoting a merchant only 2 or 3 of them and then they are attacked by maybe 4 rebels.

That would make for an awesome mod if it isnt in already. I think I may make that the first couple days with the creation kit!

Considering this happened in Oblivion through Fallout 3, probably. Many of the previous game's animosities were generated through "Hidden" factions, such as "Wildlife" faction, which is hostile towards all other factions.

If you're asking for open guild warfare... maybe that's a bit of a stretch.