The year predicted for the glacier's collapse was an extrapolation based on data and models available at the time. While the timing was off, the thing is going away visibly for everyone!

In hindsight they shouldn't have set the date, but contrast the fast decline with the long existence. Maybe even let people guess or bet the exact year to involve them and make them think.

Do you believe that current climate predictions are based on the data and models of the time?