There is no 2028 deadline. No reason to close in 2026 certainly. They have the rights to have Simpsons through 2028 whether Disney says yes or no on an extension.
So if it leaves, I think it will run through December 31, 2027 and close on January 1, 2028. The Mummy seems to be something that would make sense to take care of before moving on to Simpsons.