Not enough tanks? Call to arms! Okay thats one idea, sure, but it dosnt stop hour long queues below heroic level, or in the soul sapping 60-80 grind... my theory? Send in the bears!
Let Beast Master hunters, tank! Oh hush your cries and bear with me on this.... bear... no? phew... tough crowd, moving on:
There is already an established template for bear tanking... druids, the one class with arguablymore utilities than a hunter already, the druid can do it all, but it wasn't always that way, and in the same vein I would petition the idea of hunters tanking is no more outrageous.
No seriously, think about it, while paladins and deathknights and to a lesser degree druids, are taught as they solo their way through the lower levels, that they have a mode where they need rely on no one, they are a one man killking machine, mobs break themselves against their heroic hide, and the only one they have to worry about is themselves. BM hunters on the other hand learn from the get-go that they have to play roles in a group to stay alive... the pet goes in first, holds the agro, you don't manage the agro properly, your in trouble, meanwhile you dps, but you have to be aware of whats going on and be the healer when your pet needs it. Hunters already have the group play mentality drilled into them from the start.
Want more tanks, don't bribe the player base with trinkets, target players for whom tanking has never been an option... All tanks at present have one play style, get all up in the bosses grill and piss 'em the hell off, well yeah thats a tank alright but melee dps isnt everyones play style... opening up the tanking role to those of us more FPS than Beat'em'up would make for a bigger pool to recruit tanks from. The first ranged tank... far from having an easier time if it, would have more to do, effectively managing two roles, the job would also be more engaging for the micromangers out there and really break up the tank'n'spank metality. Besides which the new perspective on tanking would litterally give the group a new role...
Which brings me too -- how would this be acheived with minimum disruption to all? Well for a start I would limit this to the BM spec, and, of course tenacity pets (the fact the pets come in tank flavour already is a clearly a sign, right?). All that would need to change is three talents in the BM tree; an AOE threat skill for the pet, a more reliable damage mitigation or self heal for Mr. Bear, and my baby: