Originally Posted by
formerShandalay
Well, the thing with Kalec is a bit strange, because in the book it happened a bit different and before the actual Cataclysm even happened (but not sure anymore, have not read the whole thing in a long time ^^)
But really, he is unimportant at that time, because the only thing that is important is that Malygos isn't attacking the other flights anymore and the distraction caused by the Nexus War is gone. So until the Cataclysm the other dragons are free to try and stop the Lich King, when he attacks them. If he wants Galakrond before Deathwing rises from Deepholm, he needs to attack them and go for it. So he'd have a war with the dragonflights on his hands. He would win this, but not quickly. If Arthas attacked full force, they'd put up a real fight and it wouldn't just be Alexstrasza there.
Alliance and Horde I strongly disagree that they would not notice if their leaders were converted, especially if you take into account that on the Alliance side half of the palace guards and both the leaders of the Church of the Holy Light were secretly N'zoth's agents. So, no, Arthas could not have Alliance and Horde, unless he fights for it, which is another warfront opened. Would he win? Yes, but not quickly.
Unless he could go for it and take it all over in one fell swoop while everyone is still sleeping from the Nightmare-attack. I do not know how that works if N'zoth already has their souls in his grasp. Had the Scourge attacked during that, maybe it would have been good for N'zoth, because Malfurion and the druids would have been distracted.
So about that attack from the Old God forces in Dragonblight. This attack on the dragons had to take place with the right timing and after all the other battlefields were won. But! it was mainly necessary because Thrall was there and could help the Dragonflights. Had the Lich King won, Thrall would still be leader of the Horde and as such, converted to undeath. No need for Deathwing to divert resources so he could take the united Dragonflights and whatnot, no 'world shaman' ready to interfere, nothing.
Again, two problems for Arthas: 1. Time, because he'd have to fight his way to actual world dominance every step of the way and he would have to achieve it by the time Deathwing beaks out of Deepholm, because as soon as that happens, 2. he is the only target left for Deathwing and N'zoth.
And I disagree on at least Ragnaros, he was firmly under the control of N'zoth. So N'zoth takes the Ancients, (which is kind of a thing) the second Well of Eternity atop Mount Hyjal in a matter of days. N'zoth doesn't have to divert any resources to fight anyone else but the Lich King and can start attacking Dragonblight at once, without the dragonflights putting up a fight (apart from the ones that are already under the Lich King's control), no world shaman, no Dragonsoul to fight him with. Also, N'zoth brings Ragnaros to the battlefield, which does seem kind of a problem for an undead army.
So again, to me it seems more like had the Lich King tried an actual power move after winning at Ice Crown by taking the Alliance and Horde leaders and raising Galakrond, this would have been his undoing. As he would still have been Arthas at that point, he probably would have tried that.
Had he done nothing and simply acted very secretly, gathered power and put his champions into place for maybe a push when the actual fight in the Dragonblight begins, his chances may have been better, but mainly because everyone else could have acted the same way and beaten back Deathwing and N'zoth at every turn like they did when Arthas lost at Icecrown. Then walk in, join with the rest (who may have been still wary about him, but well, an ally is an ally if you're already in the middle of a fight and low on resources), wait til all forces disperse, because they won and the war against Deathwing is over and then... boom stroll over to Galakrond, raise him, conquer the world. Yes, that would have worked, because then everyone was gone, the others would have let down their guard and the armies of the mortals were fighting in Pandaria.