The story of The Scourge and The Lich King has always been important lore, and even though the original Lich King, Arthas, is no more, his replacement, Bolvar Fordragon, will return some time in the future. Probably not in the next expansion, and even not in the one after, but he'll be back sooner or later.
via Kotaku http://ift.tt/13XfbzZ