The Supreme Court may decide to deal with the issue of gay marriage in a very narrow sense, rather than a broad sense, due to the possibility that Antonin Scalia, Clarence Thomas, and Samuel Alito may influence Chief Justice John Roberts and Associate Justice Anthony Kennedy to join their side, as they do about 70 percent of the time.
But no matter what happens, the Republican Party will suffer, since the momentum of history is moving the nation toward acceptance of gay marriage, with young people having no problem accepting it, and senior citizens, a majority of whom oppose it, soon to be gone from the scene. And the Republican Party officeholders caving in to their conservative evangelical Christian base will marginalize them very soon.
It is interesting that Republicans NOT in office, more than 100 of them, have endorsed gay marriage, while only Ohio Senator Rob Portman has been willing, among Republican officeholders, to back the concept. So such hate mongers and extremists as Bryan Fischer, Gary Bauer, Ralph Reed, and Tony Perkins hold undue sway over the party, and the effect will be that the GOP will be unable to compete on an even basis for the Presidency and the Senate, although they may be able to hold on to the House of Representatives, due to gerrymandering which helps to set up rural districts that will continue to resist cultural change.
But again, in the long run of history, the Republican Party is painting itself into a corner, and burning their bridges behind them, as the population changes and social attitudes become more tolerant.