They made their ruling, now let them send their armies to enforce it.
What army? The IRS.
If it came to that, I have no doubt that Obama would. (He has precedent: Eisenhower federalized the National Guard, and called out the regular Army, when Arkansas refused to obey court orders to desegregate Little Rock Central High School.) But I don't see any sign that it will come to that: has even one State's Governor said they were going to resist these court orders?