The answer to my question is it would take 160 years, which is a lot more than 15 years.
My first point is that what you're saying is technically true, but it's a gimmick. Canada for years, at least since the Second World War, has based our debt statistics and presentations on Canada's government debt, which is $480 billion. At $3 billion a year, it would take 160 years to pay it off. That is the reality.
You are using this arcane statistic of “net debt”, which nobody, except a few economists in the OECD, has ever heard of, which includes provinces, which includes the Canada Pension Plan, and which nobody out there cares about or has heard of. It's absolutely misleading to talk about eliminating debt and becoming debt-free, because one has to use the measure that has been used for decades, and that is this one: it will take you 160 years to eliminate that debt.