I'm pretty sure that a newly negotiated "auto pact" agreement would look precious little like the one from 30 years ago.  Auto parts Supply lines are now almost world wide for any car manufactured in any facility.

And with increasing robotics, the actual man hours building the vehicles drops each year or model.

It's a different commodity for a different times.  A new strategy might be preferred as opposed to trying to recreate a policy from a previous generation.

My guess, would be the Canadian auto industry may well go the way of the Australian or Quebec model, as it is difficult for the current administration both provincially (Ontario) and federally to move ahead with a greener future and less dependance on oil and manufacturing, and at the same time have the funds to "invest" in the auto manufacture's new or upgraded plants.