When they leave, the density will drop again. Will the dev team advance the glacier again? That would be ridiculous.
If they're true to their word, then yes. Anaris said he'd advance the glaciers to a point where the density reached levels he was happy with. Players leaving the island will further reduce the density.
The glacier event has been quite catastrophic for FEI as a playing environment. As LGM Alpha said before he quit the game, the glacier was dropped on the island during the biggest and most interesting event in FEI history while it had a really good island-wide war raging that would probably have run for at least another year (likely much longer). Many players are understandably pissed at the GM event's intervention, and will leave the island (and the game in some cases) as a result or as a protest.
