There will be more interaction because interaction is tied to progression for a lot of people. Merchants needs to interaction to spread their name around, guards need to fight bandits to improve their skill, and people are a resources. Also, you won't have alts that can cover all of your crafts, you can't do everything yourself.
A big thing with WoW is also all communication is done via UI. If I need a potion from an alchemist, I don't go to a person I go to the AH. CoE will not have a system like that. Someone could set up a physical auction house but for that happen and run smoothly there needs to be a lot of interaction.
I think the worse that can happen in CoE are cliques forming. Trusting outsiders takes time in games like this, especially with spies, enemies kingdoms, bandits, trolls, and being able to lose your stuff. But like you said, it's going to be a mix since CoE will attract a lot of different people.