Lol. Still trying to be Warlock Tanks. Get over it. Not going to happen. So much of the game mechanics would have to change in order for it to happen. Where is your Block? Dodge? Parry? coming from?.
The game does not need another Tank class. There are enough. People simply do not wish to play the role, THAT is why the the times to enter dungeons and raids are so long. Blizzard could add 50 Tank classes and could not change people's desire to not play the class.
If you want to play a Tank so bad then roll a dedicated Tank class and enjoy.
Unfortunately, I agree with Shailude (even though he's a bit of a troll).
Warlocks don't get the 6% reduced chance to receive a critical strike like other tank classes do. If you bring a warlock into LFR, you have a chance to be hit for over 100k, which isn't sustainable through a long fight.
If you just want to tank in dungeons, then go for it. As far as I've seen, it seems to work ok
... The only problem I see with tanking in dungeons, is that you wont be able to need roll on tank gear. If you are able to procure some tank gear, thats great! However, you probably will only ever be able to use it to tank dungeons (Crit immunity in raids is essential).
I personally only do dungeons to improve my gear to be raid ready, so I wouldn't find tanking in them to be very useful (since warlocks cant tank raid bosses nearly as effectively as regular tanks). I know some people just enjoy tanking dungeons, but I think in general, most warlocks will want to just improve their dps gear so they can advance to the tier content.
All this aside, I think three changes would need to be made in order for us to be effective tanks:
1) Give us 6% Crit immunity like other tanks.
2) Change how Dodge scales so we can reforge to it for extra avoidance (currently Dodge scales horribly).
3) Change how Mastery scales to be competitive with how it scales in other tanking classes (currently you start at negative damage reduction from Mastery and gradually move to positive while reforging to a LOT of Mastery).
Dont shoot down our hopes and dreams.
Hopefully I didn't ruin someone's hopes and dreams... That's not my intention.