Convenient metonyms aside, Canada's "multi-culturalism" is functionally identical to the USA's "melting pot". People make a big deal out of what each system encourages and discourages, but in practice there is no difference. An immigrant moving to San Fancisco or Boston will not be "assimilated" any more forcefully or thoroughly than an immigrant moving to Toronto or Vancouver. Quite frankly, i don't even understand what multi-culturalism is. I have never seen it in action.
The most common proof of multi-culturalism's impacts are the various ethnic enclaves which dot the GTA. These is nothing to suggest that these enclaves are the result of any government policy however, rather consumer choice. Outside of Signapore, no industrialized country regulates where someone can live based on racial quotas. If we abandoned the symbolic policy of multi-culturalism, there is no reason to suggest we would and hence no reason to suggest immigrants would behave any differently than current. More over, numerous cases exist of ethnic clustering in all countries. A visit to South L.A. or Atlanta will show quite clearly that, fruitcake or melting pot, the US is in many ways far more ethnicly segregated than Canada. Even more so with the predominantly Muslim Suburbs in Europe. Even in Canada, early European immigrants organized themselves based on nationality. Kitchener (aka Berlin) even retained the German continental system of roadways!
Multi-culturalism doesn't exist. It is the logical extension of individual rights and personnel freedoms that have been building over the past centuries. Immigrants don't do anything because of multi-culturalism. Sikhs choose to live in Malton because they like it, not because some government policy tells them to preserve their culture. Barring some kind of nationalistic indoctrination and mandatory patriotism camps, a disturbing throwback to the 1930s, we aren't loosing the fruit cake or salad.