I think this is where Carney landed. Trust is gone. Further, the US and the world would have a precedence in dealing with Canada. Accepting a bad deal would maintain an illusion that this was good enough and to continue on in this direction. Once Trump is gone the negotiations could restart but at a much less valuable position to Canada.

Canada has had a long term investment and productivity challenge with too much focused on North and South. I suspect that this is now the catalyst for East and West investment.

I think the calculation was that no deal and the natural consequences are not that much worse than the deal on the table short term. And taking into account the future of the above it was going to be worse.