It is interesting - it is the first 300ER to leave the fleet after 10 years only - while there is still a bunch of non ER older frames
The 777-300 are all leaving before end of 2017. The lonely 777-200ER is still in use because restrictions on one airport in Pakistan. In 2018 there are only 777-300ER left to be retired, AFAIK 13 are planed to go. In 2020 we can see the first A380 retirement, if leases are not extended.