Bob argued that Loki is the only still living villain from the other films that would require a team to take down, I can see this..... But then there is the whole cut off one head two more grow back bit, and with the loss of Red Skull, a pretty friggen big head got cut off, so theoretically two more should grow back..... RIGHT??? Especially since we have Fury putting The Avengers together, you'd figure this means that SHIELD couldn't handle a certain problem they had previously been struggling with. So an army of evil crazy people working behind the scenes seems like a logical foe, IMO....