I still think 2016 is looking fantastic for GOP prospects. Remember too, you can't look at 2016 the same way you look at 2012. Obama won't be running again, and the Democratic field is remarkably weaker than possibly any Democratic field since 1984.
Vice President Biden - He's all but said he'll probably run, and I think he will. The problem is, unlike the Republicans who score a string of victories over the course of decades without refreshing (Eisenhower in the 50s had VP Nixon who was Pres in the 70s, George Bush was a G-Man in the 70s, President in the 90s which lead to his son being President from 2001-2009, ect) Democrats tend to constantly jump from one to another. VP = Gov of Mass = Gov of Arkansas = VP = Senator from Mass = Senator from Illinois, ect. My guess is Biden will have difficulty. Plus, incumbent Vice Presidents tend to lose elections. Nixon, Humphrey, Gore, ect or never make it there themselves, IE Barkley, Quayle.
Secretary of State Clinton - The worst fear of mine would be eight years of Obama followed by eight years of Hillary Clinton. Luckily, the likelihood of this occurring is very slim as the Democrats are reluctant to nominate older nominees.
To be honest...I think that Martin O'Malley or Andrew Cuomo look like safe bets.
I wouldn't call Schweitzer, O'Malley, Gillibrand, Hickenlooper, Warner, and others that weak. Especially if the GOP blame a Romney loss because he was too "moderate" (lol), and nominate an unelectable social conservative like Thune or some Tea Bagger. Of course a lot can happen in four years, so who the hell knows.
