Based on today's patch notes for KA going live, the best advice I can give to a Warlock is to betray to a Wizard, since they upped the damage of abilities of a class that was already beating us by a long shot in the DPS fight.
Id say best advice would be to roll a BL, cause now they have access to the new prestige conversions, along with the reset and the ravaging rune, they are gonna mop the floor with mages in general.
Yeah. If today's patch notes didn't already prove it, the powers that be pretty much just don't want people playing Warlock anymore. That's the answer, and why the class has been intentionally neglected as long as it has.