I do believe that. Unless God didn't give mankind and angels freewill, then we were destined to disobey him.

I think the reason he still has power is his way of running things hasn't gone completely south yet. In revelation, there are detailed descriptions of how satan comes to rule the world in-person for 42 months and basically causes the world to end. God knows this will happen, it's part of his plan for a new heaven and a new earth post-judgement day.