The 20% Off “Last Chance” Sale

For whatever it's worth (not much) here's what Hime had to say on the subject:

Indeed it was suppose to be a permanent feature of the game but we are doing a lot changes for Big Bang and the removal of permanent NX items is one of them. This removal was not originally intended when we launched permanent items. So right now the current permanent items will be leaving the Cash Shop but when we release new Cash Shop equipment it will have the perm feature for a limited time in case player want to pick a permanent version.

http://forum.nexon.net/MapleStory/forums...px#6183941