it look a long, long, long time for wow to implement some solutions but until someone (EQN?) comes up with something better MMOs really need to
1. make tanks the highest DPS class in game while they are tanking. wow implemented the vengeance mechanic, which gave a dps buff while you are getting hit, the harder you get hit the more DPS you do. A huge chunk of any MMO population are DPS meter whores, and they literally get buzzed from seeing their names at the top of every meter parse. make tanks always #1 and you will see a lot more tanks.
2. don't tie leveling shit to regular dungeons. its kinda bizarre, ff14 already implements solo instances and guildhests, but shoves people into regular dungeons as part of the story quest. No one is learning shit leveling anyways, people are zerging fates in bikinis using no job crystals. Dungeons should be something people want to do (more XP, better gear for leveling, crafting mats) not something you are stuck with and unable to complete your story quest without doing.
3. its ridiculously silly to have dungeons be tank/healer/2 dps. Should be tank/healer/3-5 dps. Not only will this help with queues, but will positively reinforce people playing tanks/healers since they will get better chances at loot (no competition).
4. implement queuing bonuses for the current role in demand, in realtime. not enough tanks, well tanks get an extra 1000 gil and a bag with a chance at a pet or crafting materials. Should always be flavor/crafting stuff, not extra tokens or gear.
sadly I doubt we'll see any of this, or done in ways that make little sense and far too little, too late.