You overstate my view.
All nations are heading towards multiculturalism and some are presently in that position and doing quite well.
Canada for one. We are not perfect of course but are slowly eating away at what ails us.
Multiculturalism will work but not if we continue to create enclaves for certain groups in our cities. You cannot have a rapprochement of cultures while splitting them apart.
Look at your own cities and how the cultural enclaves maintain divisions.
Regards
DL