There is absolutely NO reason why any Muslim can not submit to Sharia Law, wherever they may reside. They can do this in the same manner that religious Jews submit to religious courts, but also comply with civil law. As an example, under Jewish Law, you can only get a divorce if the husband agrees. The religious court can take steps to encourage the man to provide a “Get”, but they can not force him to do this.
BUT, religious Jews also go to the Civil Courts and obtain a divorce. The divorce is a legal step, not a religious step. Under Jewish law, the couple is still married in the eyes of God, until a religious divorce is obtained. A religious Jew would never consider remarrying, unless they had also obtained a “Get”. BUT, they would also obtain a Civil Divorce, which would spell out such things as Child Custody, alimony, etc.
There is absolutely no reason why such an arrangement would not suffice for Muslims.
The problem is, they want to impose their religious obligations and believe on to people that are not Muslim.
In the United States, there is absolutely no possibility that Sharia Law could ever be imposed. It would violate the Constitution to impose religious law on anyone.
Were our government to attempt to force this law upon anyone (including Muslims), millions of people would join a citizens militia if necessary to overthrown such a government. It would mean that the Congress had violated their oaths to “Uphold the Constitution of the United States of America”, and the people would have the absolute right to overthrow such a government.