To my knowledge Canada hasn't expressed a view yet as to whether it is investing in the bank or not.
You're absolutely right that the Americans are having a hard time with governance around multilaterals, the World Bank, the IMF, and other global institutions. They have not actually brought into force the major changes in those institutions that were negotiated a number of years ago.
I think that for the moment we're still sifting through all the information, but in my view Asia is the future. For the next 20 years, the Asian economies are going to grow much faster than the rest of the world, and there will be massive business opportunities to develop in Asia.
You can always join at a later date; you don't have to be there at the launch date. But countries that aren't members will find themselves shut out of infrastructure investment opportunities