My 02 cents, given the current PT iteration/patch notes:
Warlocks will be in a decent place in 5.2 - shadowcleave/rls is looking to be a very good comp, and the affliction buffs are pretty nice. Pretty squishy still, but they have decent defensives, including some pretty damn good ones that are usable while stunned. They won't be OP but won't be under-represented either.
WW Monks are hard to tell. Every monk and really every melee right now is screaming about survivability in stuns - really, everyone screaming is comparing themselves to the 5.1 golden boy warrior's survivability, which is getting substantially nerfed with defensive stance and overpower nerfs. It's kind of hard to tell right now considering absolutely every class thinks they are squishy and needs defensive CDs. What probably needs to happen is that base resilience needs to go up 10%, and mana regeneration goes down 10% instead of adding battle fatigue (MY 2 cents).
WW monks now and in 5.2 do extremely great sustained damage. Yes they are squishy in 5.1 and will stil be in 5.2, but they actually have and are getting quite a good amount of tools to deal with it - WW monk's mobility is really its defining ability. You have 2 rolls, a 70% spring with snare/root break on a 30-40sish CD, a port, and flying serpent kick (you can basically teleport around on a 30-40s CD). They also have decent ranged attack abilities with the way that SFB is hitting right now. That gives monks great uptime, but I also think that because they have such great mobility, this mobility is actually an essential part of its own survival/self defense. You will have instances where you run in to do some damage, take too much damage yourself, and port/sprint/fsk away to avoid damage. Self-heals are probably the worst out of all hybrids, but then again that is because of the mobility of a monk. You really only have a few defensive damage CDs - touch of karma (essentially a couple seconds of invulnerability), a crappy 20% raid wall on a 3 min CD, and through talents either an equivalent of cloak of shadows, or another talent that reduces 3 big hits by half.
Its still early to say however, and if either monk self heals are buffed or if their raid wall CD was reduced majorly, I'd say they are in a great place. The safer option would probably be warlock tho, especially considering that destro locks are so desirable in RBGs, whereas any melee but dks and rogues will have trouble in RBGs.