My campaign started in 1978. We're still playing. Over 60 players have come and gone, but the current crew has a half-dozen of the original players from the 70s and early 80s still going. We've outlasted at least 6 marriages, lots of moving (I currently Skype in, but will be moving back home next year), and all manner of turmoil. When I've been too busy or burnt out to DM, someone else in the group has stepped up to fill the gap.

It's hard to schedule because of family and work obligations, but we are pretty close to monthly.