If Clinton loses the election because of NC and MI I could see the democrats pushing for an Australian-style mandatory voting law
I don't think so. These laws are completely ineffective, nobody is going to jail or fine people because they didn't vote. Automatic registration along with soft voter ID, like the West Virginia law, is the way to go.
Actually, this is wrong. These laws are perfectly effective: Australia routinely gets an over 90% turnout. No jail is necessary: small fine, say 20 dollars, administered like a parking ticket, would do the trick admirably. May countries have been doing it for decades, and it is reasonably easily implemented.
Now, there are other reasons not to want that, but ineffectiveness is not one.