I would really love the oppertunity to be able to run Naxxramas as a 5-man group, like a big, hard heroic instance.
Today we have Trial of the Champion and the generous benefits from the emblems dropped from heroic dungeons. Good if you ask some, bad if you ask others. Point is that I was able to ding 80, run heroics, and 1-2-3, I was geared enough to do ToC 10/ToC 25.
Now, Im the kind of player that gets goose bumps from special surroundings, and Naxxramas is something special to me.
With gear in 10-man being more or less equal to the gear that drops in Trial of the Champion 5-man heroic, why not make a 5-man version of Naxxramas?
In that way, and in my opinion, players would not ignore Naxxramas, and it would be awesome to be able to take an evening, and instead of going heroic farming, you join a 5-man group to clear this awesome instance in a bunch of hours, to get gear and emblems.
Naxxramas should as a 5-man instance still be harder than the average heroics and even harder than Trial of the Champion due to the strategy aspects of some bosses, and would require some better gear than fresh-dinged green/blue-gear, but doable if you got a group with about 6-9k DPS, a hitcapped tank and a quite good healer.
That way Naxxramas would still live on and would not be abandoned as it often gets on some realms, because it is an really awesome instance.
And ofcourse, we would want 5-man versions of the "Sapphirion's Demise", "Kel'Thuzads Defeat" and "The Fall of Naxxramas". ;-)