Given the current level of pecuniary embarrassment of the provincial government, and the obstinancy of the federal government, I would say that the status of this plan would have to be considered in the realm of
"when hell freezes over". 
I am afraid we are looking at the new paradigm for the mighty Petitcodiac. A permanently narrowed (but ecologically healthy) river channel, with the old headpond above the causeway gradually silting in and reverting to marshland just like the river downstream from the causeway.