I spent some months in Australia and got a completely different idea: multiculturalism is completely an illusion. It's a "timebomb" slowed down by abundance of resources: while everybody is getting more then they need, everything is ok.

Edit: For half a decade I was an expat in a monocultural country. Being open-minded (giving in more often than demanding) and member of a too small community to be considered a threat I could enjoy peace to a greater extent than everywhere else before - even as a member of the majority group in my own country. Probably that's why I'm very bearish regarding multiculturalism.