I'm don't quite get what you are saying, but I also note, you are just saying it without backing it up in anyway.

Why wouldn't it last?

Why can't some members be incompatible with others?

Why must there be a framework to make judgements on others?

The United States is a good example (in a lot of ways) of successful multiculturalism (it's a bad example in some ways as well). But no official language, no restrictions on belief, the only consistant thing is a 'rule of law', is that what you mean by a framework for judging?