I missed this the first time around. I'd argue there are only a handful of courses in Canada that could be considered great, and yes, the new Cabot Links is among them.
St. George's is already recognized as being among the best in the world, as is Highlands Links, though the later's reputation for questionable conditioning had really hurt it over time. Yes, it has one of the great routings in the history of the game, but it is too wet, and has significant issues in overall administration that hurt it. It is still my favourite place to play in the country.
Beyond that is Hamilton, which is in dire need of a architect with a vision for Colt's work (please, dear God will someone at the club notice that Gil Hanse has that background, or that Tom Doak is in Michigan and take it out of the hands of Tom Clark), Sagebrush, which I think is tremendous and flawed at the same time, Banff and Jasper (both of which suffer from conditioning issues from time to time) and the National, which I think is simply too close to many other above-average American designs to really set itself apart.
Finally, there's the rarely seen Goodwood, which is a terrific course outside of Toronto that is exceptionally solid, but perhaps never elevates itself to the "great" level.