I agree With this, no reason to do anything until after the 2028 season, If anything happens after that It would be time. Now that every opening day attraction is now gone from hollywood, its going to be easier to replace springfield as it would be 13 years old by then. I really don't know what would be able to replace it though. It just unfortunate that springfield works so well as a is right now, it will be sad to see it go.
What doesn't do the area any favors is that, while receiving upgrades in 2008, the Simpsons ride system will be closing in on 40 years when 2028 rolls around.