well what's happening now is that asmo side is dying due to that noone wants to lead siege, even your "join the darkside" rewards wont help. Boosting GP in allys and remove in groups are a good suggestions imo. I stoped going in allys when most ppl stoped, due to that I am high rank, and need a alot of GPper day to keep my rank.
Last time this happened to ely side, asmo side stepped in, gave ely side a fort, to boost them (abyss one). And if I am not wrong in my memory, our siegelead back then even talked to elys side about finding a leader.