That would be simply incredible if Buzz got replaced and CoP didn't. Especially considering that Tron is a much less popular IP than Toy Story.
I actually think Tron is a better fit for Future World than Tomorrowland. I think Tron is one of the very few IPs that is 100% appropriate for EPCOT, one of the venues originally planned for CommuniCore was even a Tron arcade. Both EPCOT and Tron came out in 1982, and both introduced the core ideas and concepts of computers to the masses. They are (or were, in EPCOT's case) both something very much of the modern day that represents a step towards the future.