The difficulty here is that gubmints really have no 'desires' that can be furthered by continuing work on the space station. On the other hand, there are numerous fields of endeavor that have private firms that would benefit from having a presence in zero-g, pharma and materials come to mind. We need to come up with a way to treat ISS like Antartica, so that a private firm that has the desire and where-with-all to get there and hook on can do so with the understanding that the fact of being able to get there ensures there right to be there once they arrive.