We don't even know if that is the final or only way co-op works anyway.
I'm thinking Secret of Mana co-op type for offline. Let me give you an example:
-I'm playing the game on my own. Recruiting a Party member(Archon Mage). I have played enough to reach level 5 with my characters.
-My brother enters the room and asks if he can join in on the fun. He will be controlling the Archon Mage (lvl5). We play for two hours and we are now level 10. We can both equip our characters with dropped loot. But wait, my brother has soccer practice and needs to leave. I continue the game without him.
-I played from level 10-15 on my own.
-Bro comes back from practice, picks up controller and is now controlling level 15 Archon Mage.
This mode would be a good way to introduce a casual player to the game.
I also think we will have the usual 2 player co-op a la Champions of Norrath & BG: Dark Alliance.
Speculation? Yes.
Yeah. thats what I'm expecting too.At least for offline co-op.