The affordable welfare state

In this article about productivity, Arnold Kling says the US's 3.39 percent growth in productivity from 2000 to 2005 augers well for what he calls the "affordable welfare state", which will require moderate tax increases nonetheless.

The Canadian economy is sadly much less productive than the American one, primarily because of higher levels of regulation, taxation and unionization. How affordable will our welfare state be as boomers start claiming their pension and medicare entitlements?