I'm very surprised they're closing it so early with a 3-year gap between iterations. Since the new version is completely detached from the existing building I don't know why they couldn't leave the original running longer. Maybe it's just a money pit, maintenance-wise, so they're cutting their losses, but what do I know?
Edit - About two seconds after hitting submit I had a thought. Maybe they're actually going for a Guardians-style system and even using the original building with a launch, just like UoE became the station and queue in Epcot while the actual ride is in a separate building. That could be fun...