Who cares if we close the door? The case for rail to Cambridge will never be there. Not least on this corridor. The population and travel patterns will never be the right mix to make this a wise investment. Canada's population will start shrinking before then. In that case, if the land can be put to better use if not needed for rail, it should be used that way.
Cambridge to Guelph GO checks all the boxes of a vanity project. Cambridge wants higher order transit just so they can brag about it. They are not interested in actually creating the best transport links. If they actually push to get this and stage 2 ION funded, the province and Metrolinx will laugh in their face. It will be years wasted.
We need busses, and lots of them. Projects like this distract and deflect from doing the things that will actually improve connectivity and peoples' lives.