You'd have a better chance of success with an exciting an novel idea. They're already plenty of military types and warbands. I also think a clean break from OotRB with fresh new characters, created with the new guild in mind.
IMHO the biggest issue with rp in games like WoW is that people create a character they want to play, then try to shoehorn it in to whatever guild they choose. How much better things might be if it was the other way around. Decide on the guild you want to create, then make characters that fit that guild.
The hardest part is that elusive, exciting idea. Off the top of my head ...
<Sky Pirates> flying round Azeroth, having adventures and stealing your treasure. Blood Elves, Orcs, Goblins (of course), a few trolls and the occasional Panda or Undead. Encourage members to be engineers and have flying machines rather than creature mounts. Work towards gathering mats to make rockets for people. All kinds of saucy, piratey, steam punky fun
That's the kind of brain storming you wanna do. I'm sure you can come up with lots of good ideas.