The political reality at the moment – and one must stress that the reality might well change – is that full marriage equality will not come into being until the national Constitution recognizes it – either by court interpretation, or by formal amendment. In the near term, it is hard to predict that the end of this reality is in sight.
That kind of approach can only work in states where politics or court rulings have already established some foundation of equality for gay and lesbian couples, and the number of states that have done that is not a lengthy list. So, in the states where that foundation does not yet exist, marriage equality will only come about through either a bold new court declaration, a change of heart in the state legislature, or a new wave of popular support that can carry the day in a voter referendum.
There is, of course, one other way: the U.S. Supreme Court could be asked, in the quite-near future, to rule that same-sex couples do have a constitutional right to marriage equality. The Justices may be presented with that fundamental question sooner than some have expected. When that test does arise, as it will, what has been happening in the states may well help to shape the Justices’ reaction, but there is no guarantee of the outcome.