When this happens, at some point in the universe, a bubble will appear. Think of it as an alternate universe (though it’s really the same universe with different properties). This bubble will expand in all directions at the speed of light and wipe out everything it touches. Eventually, this bubble will destroy everything in the universe.
But don’t worry: The universe will still be there. The laws of physics will be different, and there might even be life. But the universe wouldn’t be anything that we could comprehend.