If ether is like energy then that would mean it could either bend or turn into to something else but it wouldn't cease to exist, and a assuming that ether in this case is primordial energy that existed along side by gravity and other forms of matter and energy.
If that's the case then if the ether of the universe disappeared then then the world would become weak but not undergone any type of reality collapse, if this ether energy took the other forms of energy with it the the universe would probably have a entire reality collapse that could be felt across the multiverse. But that's just what I think on the matter if anyone else has better I'm all ears .