I think they will do something to keep them relevant.. but not until there are more raids available.. I wouldn't be surprised by a relevancy patch around the time of the comet, at which point excluding the new raid there will be 3 other raids to turn into a new event. I call it exotic raids. on a monthly rotation there is an exotic raid made from all but current raid. it functions at or 1-2 levels below the level cap, each month is picks one, and grabs a random selection of nightfall modifiers with guaranteed heroic modifier. you'll only get credit/drops once a month per character.. but all weapons and armor dropped in said run are scaled up to current maxes equivalent to current raid gear. not only would this keep weapons relevant but it would allow for variation in maxxed level gear. oh and a guaranteed exotic engram for completion of the raid. that's my preference.