The only way Gore will run is if he is 100% sure he will win. He's not going to risk another loser run.
He likes being at Sundance. He likes being at Cannes. He likes putting together documentaries and I think he liked teaching at the college. Gore doesn't deal with pressure well. At the end of the 2000 campaign, it was obvious he was sick of being told what to wear, to keep his weight down, being pumped with answers for debates, and being confrontational. He's not a confrontational man by nature. That's why he came off so badly when he tried to bully Bush in the first debate.
Gore might run again, because he detests Hillary. I don't think he's ever forgiven her for kneecapping him as much as she could in 2000. But at heart, he doesn't want to be president. He wants to do what he's doing now.