To add to the many other better arguments to keep supply management. 
Virtually every other western country subsidizes there dairy farmers from general tax revenues making all citizens pay for cheap milk that millions of them don't drink. In Canada,  only those that buy dairy are responsible for subsidizing the farmers and producers with set prices that insure a decent living for producing a high quality product.

In Addition the whole reason this has come up with Trump is because there is too much dairy product, globally and it has become hard to sell expanded volumes even at a loss. It makes no sense to "transition" to a system that does not need our milk at this time and enjoy the stable safe and well managed supply of dairy products that is the envy of the world.