What worries me is that if Vz can reneg on a contract who says they'll maintain their agreement with Canada re: the investment treaty.

I understand that Canada exports a lot of food (grain) to Vz (please verify) and some sort of severing of ties or political dispute would harm Vz. I doubt the Canadian Government would stand up that much for little old KRY. The Equador situation will be a good test case though...