Huh, i wonder, how much would have changed if the DnD was less black-and-white and there would be no alignments. I mean, most look at alignment description and if it is "good", they assume the character can never do anything wrong without "falling", and all. Actions are what matters. What if, if Eilistraee became "neutral", she would become in some way better? For example, more gender equality, a lot more active work against the spider-kissers, less of "destroy anyone we believe evil!" and more of "Destroy anyone who actively harms us or one or those we care about.". Would the "neutral" tag/label still be so baaaad?
All that being said, i seriously doubt Eilistraee will become neutral. The pantheon needs a goodie-two-shoes, after all

. And both Eilistraee and Vhaeraun have their fanbase. Besides, the Masked Lord will get back what belongs to him soon enough. Maybe, some time spent with the Shadow`s portfolio would make Eilistraee a little bit closer to neutrality, but definately not enough to change her alignment. V would love for his sister to stop believing only those dark elves who follow her or accept the rules of the game have the right to live on the surface. That would mean much less trouble for his followers, and maybe an occasional alliance against their dear mother

. But attempting to pull it off would be much more trouble than it`s worth. So do not worry, there is hardly a good reason why Eilistraee would change her alignment in the end.
Cheers

Dont try to catch the wind.