First and foremost: No, this isn't a request to faceroll the Sarnur we have now.
This is a suggestion that extra wings/chambers are added onto what is already there. Sarnur gets progressively more difficulty the further in you go. Partly because of the requirement for dwarf-make damage and partly because the mobs are simply tougher (such as the trolls and whatnot). Considering 2014 is a year without an expansion and full of revamps on other areas (North Downs, etc), it occurred to me that it would be cool to revamp Sarnur too.
What if we had wings in Sarnur that were for levels 55, 65, 75, 85 and 95 as well? I'd recommend dropping the requirement for dwarf-make damage in these higher zones (because by these levels we are into Legendary weapons and dwarf-make damage isn't generally as valuable), but it would still be cool if new areas within Sarnur could be added.
Then add on even more barterers (perhaps move them all to that little outpost just down the road from Sarnur) for each of the new wings. Put in some cool stuff for each level set (gear, recipes, etc). Throw some quest NPCs in, with daily quests for each level set.
Within the new Sarnur wings themselves, add new named elites -- though please not on such dreadfully long timers (in fact, it'd be great if the timers of the existing 6 named mobs were reduced considerably -- make them into boss fights of sorts for the first part of Sarnur, with respawns within moments). Whole new sets of deeds could be added in as well. Mobs could include more drakes, of course, as well as spiders and other creepy critters. Within each wing there can be a less densely populated part for the more casual/solo of players, and the further into each wing you go, the harder the mobs of that level get.
Seems like a fun way of reviving interest in Sarnur. These days people mostly only go there for deeds or for grinding Thorin's Hall reputation. This would provide new and fun content for all of those 45+ levels. New daily content, new rewards, and the foundation to provide more wings each time the level cap rises.