What happens to the last Lich King Legendary quest when not handing it in...

[crunk001]

I wonder, my first time that I complete this questline. Never had the interest to do so prior to now and that I now have completed it "Sealed Chest" in my inventory, quest completed but not yet handed in. What happens if I simply start the quest for the chest abandon the main-questline? I can take the quest again after looting all the items, but there is no more chest shown as reward, rather abit more gold.

Will it stay that way or possibly glitch and yield the same reward?