I really like the new tanking glyph and I think its a positive step to draw ppl to the class. We've received multiple abilities to mitigate and prevent damage. It appears to me that a tanking warlock is the next step in light of all the changes to the class. Reading the forums there have been a lot of warlocks who have taken this glyph seriously.
I believe in a patch down the road blizzard should consider making a viable tank spec for warlocks and let us que as tank for 5 mans/heroics. The game needs more tanks, the ques for 5 mans as dps can still be fairly long especially during off peak play-time hours. I don't think warlocks should replace raid tanks though. High end raid tanks have always and should always be a warrior.