Actually I think they can stay fun indefinitely if they are fidgetable and to be fidgetable you can make those animations rendering and acting differently according to the user input.
Back in the day, the lock screen of the iPhones hand a physics based bounciness. When you slide the lock screen from the top it would slightly bounce at the bottom and if you accelerate the lock screen it would bounce more. I fidgeted with that all the time, I was sad when they removed that.
UIs become so boring, I hope and expect to get some skeuomorphism back. Our current devices are so capable that this time the skeuomorphic designs can be much more convincing.
Back in the day, the lock screen of the iPhones hand a physics based bounciness. When you slide the lock screen from the top it would slightly bounce at the bottom and if you accelerate the lock screen it would bounce more. I fidgeted with that all the time, I was sad when they removed that.
UIs become so boring, I hope and expect to get some skeuomorphism back. Our current devices are so capable that this time the skeuomorphic designs can be much more convincing.