These two statements don't agree... you can't have an attraction that does not induce demand, but also relieves capacity. Capacity is useless if it isn't used (See: Carousel of Progress).
No I don't think that Tron will reduce the wait time for Pirates, and that's exactly the point: you will still have capacity issues in the park, because people will still want to experience the "must-do" attractions. Except now you have slightly more people in the park to see the new ride too. Assuming people are still spending the same time in the park, and experiecing the same number of attractions, all you do by adding new attractions is make the already underperforming attractions even less relevant.