US airlines have been serving Cuba for quite some time now, and a lot of Canadian businesses have done business in Cuba for years without regard to the old embargo. Air Canada has been flying vacation trips to Cuba for years without any impact to its US business, even when the embargo was in full swing.

Remember China needs Canada more than the other way around - Canada can sell its oil and resources to other customers, China cannot grow enough food to feed its population and Canada can easily cut off food exports to China and sell them elsewhere, just like the USA will do assuming the trade war really gets going. You can never be secure relying on one customer - this is one of the most basic rules of business, but has been violated for decades by countless companies and governments who thought they could enrich themselves through investment in China, but instead the opposite happened. This is as good a time as any to cut the cord and move on.

Air Canada is being decimated on social media over this decision, and almost none of the comments are in favor of the change, but almost universally deriding it.