You can’t “force” them to assimilate. The only solution is to get rid of them.
Burn their mosques. Kill their imams. Deport, shoot or hang the rest. All of them.
They and their children will assimilate over time as long as the rest of us don’t bend over backwards to help them remain isolated. IE providing Good & service in their isolated language and custom.
But Bobby Jindal is right the more they try to cling on to their old customs and ways the more isolated and poor their community will be(for lack of the trade and cultural skills necessary to interact with the surrounding Good, Service, and Job market).
Poverty and feelings of cultural identity threat from the world around you tends to breed resentment and can to lead to danger for outsiders. Particularly in conjunction with the Democratic parties racism based Minority politics of hate, envy and resentment.
The end result is very much what we already have in many black communities, areas where outsiders particularly other ethic groups cannot go safely. Or as Bobby pointed out “No-Go Zones”. The other long term consequence of this baliziation of the US are more serous on a large scale political and economic perspective.