It's possible the 1990s model of multiculturalism only failed because people moved away from it, 1990s multiculturalism was never, ever predicted on openly hating and being racist about white people, things only started to go to hell in a hand basket when anti-racism meant "except for white people"
Back in the 1990s it was white supremacists who were the trouble makers rocking the boat whereas everyone else just wanted to be left alone, today it's the left who rock the boat.
It used to be about just about treating everyone with respect and white racists were the ones not willing to do that, but now it's the left that refuses to simply treat everyone with respect.
Had people always stuck to the 1990s mindset I doubt things would ever have gotten this bad, but people chose to radicalize and this is what we get.