Sylvanas will have to be stopped at some point. She's like...the Lich Queen now. Give her enough time and I'll bet she can raise more soldiers than the other races can create the old fashioned way, and then what? Is she just going to sit on her laurels? Probably not. She already took land in Cata...of course she was ordered to attack Gilneas by Garrosh, but no one ordered her to go ape shit on Hillsbrad, that was her idea. She's obviously hungry for power and control. So I see attacking her, and thus attacking Lordaeron, as inevitable...but you're right it won't be about resources, or even faction pride, but out of necessity.