A massive engine, to drive a twisted wheel, that will pull it like a pump through a pinhole. As the galaxy becomes more self contained, the pinhole continues to narrow beyond size, and the pump gathers strength, until the last wisps of smoke disappear beyond our dimension. What escapes will be part of the cosmic soup. (Thin Soup.) Fortunately, as most things universal go, it will take some time.
As far as we know.