For many years, it is expected the Supreme Court to rule on the equal marriage and it's probably better that it comes as many US states have legalized marriage equality. This makes the federal equal marriage as the logical conclusion.
Of course, we still don't know the decision of the judges but they will make it this year. In 2015, there will be a federal marriage equality in the United States or not.
Everything will start late April with this question: Does the US Constitution guarantees the possibility for same-sex couples to marry, just as between a man and a woman?
The response of the Supreme Court will be then known late June.
At present, only 14 states have not legalized marriage equality but in many of these states, federal courts have already repealled the marriage equality bans and expect judgments in courts of appeals, which, in my opinion, won't makje any decision, preferring to await the decision of the Supreme Court.