There is a permanent Motes of light vendor. His name is the Speaker. Unfortunately he only accepts year one raid materials. (Ascendent and Radiant shards and materials) and he'd give you either Motes or Glimmer. Also, if they bring back the wolf packs, they should bring back the swords of Crota. These events only last for the current DLC. Once the rise of Iron releases, the Taken infestation public events will also be gone and be replaced with whatever the Rise of Iron has to hold.