My shadow priest would disagree (with regard to PVE anyway). We have Fade. If that's not a threat dump I don't know what is. Unless you don't think of shadow priests as hybrids.
Not to mention every Druid has Cower (though they have to be in Cat and melee range to use it) and every Shaman should have Wind Shear, unless that's been removed since I last played mine (pre-MoP). Technically the only "hybrid" I can think of that doesn't have some sort of "threat-altering ability" (since some people are getting bitchy about the words "threat dump") is Warriors.
Oooor, he does and that's why he says 'more then likely'... It still stands that GC won't post here, even if he does read it, so if you want anyone from Blizzard to read and respond, posting on the official forums is the way to go.