This is not news.  There are always risks and error limits in long term predictions.  The first rule that actuarials learn is that their answer is almost always wrong.  

In the 1990's the government realized that CPP tax rates were too low to fund obligations so what did they do?  They increased them.  Meanwhile those who went on CPP shortly after got a benefit from revised numbers while those who were entering the workforce were overcharged relative to their expected future pensions.

The actuarial numbers should be reviewed annually and adjustments made every few years to ensure the pension system remains 100% fully funded for future generations, and yes, they will eventually have to pay more if interest rates remain at current low levels.  But given the history of interest rates over my 50 or so working years I expect they will rise again in the not so distant future.