He will be 68 years old in 2016 - he could make another run for the Presidency.
I don't think he will. He is having a good time writing books (his first career, before politics was as a journalist) and making lots of money. Being a politician is not all its cracked up to be, the truth is being a journalist is more fun. His split from Tipper and the sale of Current TV to al-Jazeera might be fodder for the opposition.
Plus, campaigning is hard work and by most accounts Gore did not love it - not the way Clinton did. And running brings with it the risk of losing - one can easily imagine that Gore is not ready to go through that again.
Finally, politics can be like TV - the people want a new face. This goes for many leading political figures. Gore has been on the national stage since his first run for the Presidency in 1988 (25 years ago). This also applies to some other likely candidates. Hillary, in this regard, suffers from her association with her husband - we've now had 20 years of Clintons on the national stage. Biden first entered the Senate in 1973 and ran for President in 1988. Jeb Bush, on the Republican side, suffers similarly. After two Presidents Bush and a Bush in national office for 20 of the past 32 years there is no particular hunger for another President Bush.
The irony is that these well-established figures often have the resources needed to win the nomination, but then can't win the general election against a fresh face. None of this by the way is a comment on the merits of a any of these figures as a potential President. But still, it is an intriguing possibility. If, for whatever reason, Hillary and Biden opt out and none of the Democratic party's 2nd team gets traction in the 2016 primaries, is a draft Gore initiative out of the question? He remains and impressive, engaging figure who brings up issues that resonate with much of the party's base. And Gore has the intriguing quality of "what might have been" had things in 2000 gone just a little differently.
It makes me think of the end of Hemingway's The Sun Also Rises:
“Oh Jake," Brett said, "We could have had such a damned good time together."
Ahead was a mounted policeman in khaki directing traffic. He raised his baton. The car slowed suddenly, pressing Brett against me.
"Yes," I said. "Isn't it pretty to think so?”