What if Anet decides to limit the benefits to just 5? What do you think the benefits would be?

Honor/Gwamm=would be a nifty emote, something on the lines of KOABD +1 = a plain Divine Aura. with each rank, it becomes more divine, and godly.
Devotion= would probably be an ancient Dragon minipet, probably Primordus or Drakkar.
Fellowship= Adds an GW2 only elite Ranger pet, or one Hero from the GW2 story (as a artificial sidekick) or both.
Valor= If the weapons work the same way in GW2, then I'll asume gold max inscripable choice of a unique skin, lets call it "Moument Weaponry" for each weapon, it's not going to be necessarily Destroyer. you can get a weapon but this applies only to your class choices. and Wand/Foci and Sword/axe and shield goes together in pairs.
Resilience=GW2 only based armor skin, Prestige/Elite level armor with lot of detailing, max armor. probably the highest tier of prestige in terms of difficulty and time to obtain.
Also GW2 HOM would be a carbon copy of what you have in the GW1 HOM right now minus the rainbow phoenix.