16 years ago
He might be dead, he might not.
I think the series will be better with Dumbledore dead, in each book starting from GoF, one of Harry's friends/mentors dies. That way, in the seventh and final book, it will just be Harry against Voldemort, without any help from anyone.
But Dumbledore might be alive too. I have a pretty wacky theory about Snape and Dumbledore both taking the polyjuice potion to be eachother. Maybe it was Snape who died and Dumbledore took his place. But...knowing Dumbledore, he wouldn't kill anyone. Or maybe the real Dumbledore went into hiding and someone else took his place and went with Harry to get the horcrux and died.