Blizzard has said they won't give a legendary that isn't too broad as to be only usable by 1 or 2 classes
as well as they don't want broad legendaries that were usable by say, all casters.
Also, they will never give healers a legendary, because it would become mandatory for every healer to have one.
Ulduar, anyone? But maybe you mean never again
Blizz has more recently said that Legendaries will be harder to get, and usable by fewer. The Firelands legendary got to be a problem because there are two kinds of ranged: those with access to a legendary, and hunters.
Until the next legendary is announced, I will continue to speculate that the next legendary will be an agility staff or polearm for Monks/Druids.
But look at it like this: http://www.wowhead.com/achievement=5010
1) Caster Staff - Vanilla
2) 1h DPS Sword - Vanilla
3) 2h DPS Mace - Vanilla
4) 2x 1h DPS Sword - BC
5) Bow - BC
6) Healing Mace - Wrath
7) 2h DPS Axe - Wrath
8) Caster Staff - Cata
9) Rogue Dagger set
Hunter weapon and healing weapon have each shown up once. Everyone else has had at least two, maybe three "turns". It is either time for hunters to get another one, or a healing item, or something new.
As for new, there's never been something that agility druids could use. There's never been a shield of any kind.
I'd think a shield would be a good option. Let Holy Paladins and the resto/ele shamans use it too - which version (tank or caster) you get depends on which way you go with the quests.
I've gotten the impression from somewhere that Blizz feels like a weapon is a better Legendary than a shield, but I for one care more about my shield than my weapon.