Read the article again:

''By 2036, the agency predicts, as many as 30 per cent of all residents will not have been born in Canada. Another 20 per cent of the population will be native-born, but with at least one immigrant parent.''

That means 50% of the population would be 1st or 2nd generation immigrants. Not that the population will be 50% non-white. Remember, Canada gets a non-trivial amount of immigration from Europe.