that would only be needed if the federal DOMA fell in the SCOTUS.
Federal law will never ban gay marriage in the states - it will ban the inter-state recognition of it, but that's all. the states that want gay marriage, or that have a political system that denies the people the right to decide it, will have gay marriage.
like NJ does now.
I believe that the trend in Vermont, Massachusetts and now New Jersey (actually the result of a many year long orchestrated campaign by gay activists and liberals in the legal field to create new law in the marriage area) shows that we cannot trust that Federal judges will not overturn DOMA some day. I certainly don't trust liberal judges not to interpret elastic constitutional provisions to impose their social agenda in the area of same sex "marriage".