It's 'possible' she's a dreadlord but I don't find it likely at all. She just walked away from a position of influence, and could easily secure herself away from random paladins and dks given she's the head of the freaking council. Or was, before she left that position of power among the center of the alliance and horde efforts to claim the broken isles and the pillars of creation within. That's just too juicy of a position for a dreadlord to pass up imo. Why walk away when she could use that position to try and cause another Purge like incident or try to sabotage Dalaran and send it into the sea etc.
No no, i don't even think that's going to happen, just was playing devils advocate.
Note: Also as the head of Dalaran she couldn't have evaded all the differents meetings with important people (Aka. those that are fighting the Legion, those that work with the differents class factions (including paladin and DH))
Being exposed is a possibility, but ultimately if she was then the dreadlord would at worst be killed and sent back to the Nether. Sure maybe there's some risk involved in staying in Dalaran but that's offset by the use of Jaina's political power in Dalaran. For Jaina it makes sense for her to leave, not wanting to deal with the Horde in any way. For a Dreadlord, they would be throwing away a LOT of influence over something that to them would be petty. Would things REALLY become THAT much more dangerous as far as being exposed if 'Jaina' just reluctantly accepted the vote and opted to remain to keep an eye on the horde, compared to still staying in Dalaran without the horde?
Also, this part isn't directed at you but rather the 'jaina died at theramore' image in the thread earlier, even if Jaina is a dreadlord NOW somehow she most certainly was NOT killed in Theramore. Not only does the noel have chapters from her point of view that make 0 sense for a dreadlord, but a dreadlord wouldn't have stopped the elemental tidal wave and would have been more than happy to see it and Varian's fleet wiped out by it, and wouldn't have let Kalic talk them down.
A better correction is we've lost Garrosh, Vol'jin Cairne and Thrall to whatever the hell he's doing, three war-chiefs and a much loved WC3 character. Most alliance players will cite neutrality but at least they're still alive, Blizzard just kill ours off.
Not to mention Cairne was killed off in the most stupidest of ways and Magatha fell right into the big box of unresolved story plots.