If something is going to cause this line not to be built, it's likely to be some major unexpected problem of a technical or engineering nature causing the budget to blow up.
On another note, since this thread is kind of redundant at the moment given that we already have a rapid transit developments thread, I nominate that this be the SSP Ottawa Confederation Line Construction thread. So hopefully lots of construction pics...
For anyone reading this thread in the years to come, especially if you're not from Ottawa, here's the City of Ottawa's light rail website:
http://www.ottawalightrail.ca