First of all, Congress does not have to pass a law. The words in Article III are, "with such exceptions, and under such regulations as the Congress shall make". Regulations and exceptions AS THE CONGRESS SHALL MAKE, not "pursuant to law".
Congress' power here is plenary, it does not require a Presidential signature, and a Presidential veto is not permitted.
Secondly, I'm sure you are right that Congress lacks the balls to do this.
But, if it were to be done, I would favor a narrow regulation barring appeals pertaining to State marriage laws, at least at first.
In my opinion, the only way forward on this is nullification. As you've noticed NOT ONE governor has called for such action. NOT ONE has called for demonstrations in the street. In fact, over the weekend NOT ONE Christian leader that I've heard of has called for Christians in the street protesting, and I've heard of no such protests anyplace. I've heard them saying "civil disobedience" and by that they mean they personally won't marry homosexuals. Well, that kind of action will not be forced by the new tyranny for some time.
We will within 2 decades, imho, be the old Greco-Roman culture, which the Apostle Paul operated in effectively, but with danger. Polygamy will become law. Drugs and prostitution will be legal. Idol-based religions will flourish. In my opinion, we are entering 'the great falling away."
I suppose revolution/rebellion is another way forward, but I doubt seriously that people who won't get in the streets to protest will get in the streets to fight.
Article I, Section 7: "Every Bill which shall have passed the House of Representatives and the Senate, shall, before it become a Law, be presented to the President of the United States;[2] If he approve he shall sign it, but if not he shall return it, with his Objections to that House in which it shall have originated, who shall enter the Objections at large on their Journal, and proceed to reconsider it. If after such Reconsideration two thirds of that House shall agree to pass the Bill, it shall be sent, together with the Objections, to the other House, by which it shall likewise be reconsidered, and if approved by two thirds of that House, it shall become a Law. But in all such Cases the Votes of both Houses shall be determined by yeas and Nays, and the Names of the Persons voting for and against the Bill shall be entered on the Journal of each House respectively. If any Bill shall not be returned by the President within ten Days (Sundays excepted) after it shall have been presented to him, the Same shall be a Law, in like Manner as if he had signed it, unless the Congress by their Adjournment prevent its Return, in which Case it shall not be a Law.
Every Order, Resolution, or Vote to which the Concurrence of the Senate and House of Representatives may be necessary (except on a question of Adjournment) shall be presented to the President of the United States; and before the Same shall take Effect, shall be approved by him, or being disapproved by him, shall be repassed by two thirds of the Senate and House of Representatives, according to the Rules and Limitations prescribed in the Case of a Bill.