The bottom line is that all the Canadian tobacco companies combined are worth probably around $10 billion, with PM's piece about 1/3 of that. PM has basically already written that off by deconsolidating their RBH subsidiary in March of 2019.
Potential verdicts against the tobacco industry in Canada for $600 billion are therefore a pipe dream. If any significant amount over the net worth value is tried to be enforced, all the tobacco companies will just bankrupt their subsidiaries and walk away.
So what leverage does the Canadian government have? Sure they can bankrupt all the Canadian tobacco companies and seize their assets, which would consist of a few billion in hard assets and the value of the cigarette brand names in the Canadian market. If they do that, then who supplies the Canadian market with cigarettes going forward? Foreign companies just importing the cigarettes? Black market? Government run tobacco companies? Good luck with any of that.
In reality, the tobacco companies hold most of the cards here. The Canadian market is not big enough for any company to put new money into it, unless they are protected from liability. It is also not big enough for the companies to agree to onerous provisions, unless they can make money there going forward. And does anyone honestly believe it would be in the national interest to outright ban cigarettes?
So what will happen there is probably similar to what happened in the US. They will settle for some big sounding number, but other than some small money upfront, it will fundamentally be a tax on future sales of cigarettes paid for by Canadians who continue to smoke. The lawyers and politicians will grab pieces of that tax, claiming to be heroes, when all they are fundamentally doing is taking public tax money for personal gain. And PM and the other tobacco companies will resume being able to earn profits and will hike prices even more than the settlement tax.