The Silvermoon Remnant was a planned reputation faction which included certain high elves found in game, but not all of them. The term has received only a single reference in the patch 1.6 notes, and nowhere else. High Elves now have their own distinct faction -- "Silvermoon Remnant". This faction is allied with the Alliance and is at war with the Horde. Not all High Elves are a part of this faction. The Silver Covenant was probably inspired by this faction as a high elven beacon in the alliance.