Does anyone expect that to hold? It seems obvious that they just needed something that seemed vaguely like a legal basis to justify the decision. It's at least not as egregious as Griswald, but I definitely think they're reaching with the "feds can't have a custom marital definition". If they're going to say it's illegal for the federal government to define marriage because marriage is a state-level thing, they may as well also say it's illegal for the federal government to consider marital status altogether.
Well and beyond that, they're setting a strong precedent for future state's rights cases. I happen to be in favor of that by the way, despite ambivalence towards this particular issue.
Well, I'd expect it to before the Supreme Court on the merits fairly quickly, now that the Nevada and Hawaii the Ninth Circuit cases that were on hold pending the Hollingsworth and Windsor decisions can move forward.
What you want to happen will happen through the judicial branch, and the composition of the House and Senate will be irrelevant. I'm guessing three to five years.