Slavery wasn't the "tripwire" issue between North and South. It was THE issue that caused a sectional divide between northern and southern states. For instance, Arkansas had more in common with Iowa than either state had with South Carolina or New York. The only major common factor between Arkansas and South Carolina different from Iowa...slavery. Even the designators "North" and "South" were synonymous with "free" and "slave' states.

It is impossible tell whether there would have been a different kind of sectional war without slavery. Certainly there were other sectional factions as you mention (East versus West, etc.). I don't believe, however, that these factions (as they were) were significant enough to cause a major war.

I completely agree with you that human nature often leads to conflict, as people guard their interests and their hold on power jealously. This type of action does not always manifest itself geographically, though. Political parties are the most common form of political battle, and they generally do not follow strict geographical borders (that is, until specific interests come into play).