How about making updates to the old raids with new levels when the level cap is raised? Add a level 32 difficulty to VoG and have it drop level 32 gear. When HoW drops, add a new VoG and CE difficulty, and have them drop the new level gear. This way weapons don't become obsolete and there's actually more than one armor set that can get you to the level cap. Would also add a reason to keep playing the old content.