Being on the Horde and the large amount of work it would take to make them Alliance or even neutral for that matter, I can't really see it happening.
But thats not what I'm trying to get across here.
I want to know why people want the Blood elves on the Alliance in the first place.
Why do you want another elf race to play?
Are Night elves not enough?
If your that desperate to play a Blood elf then just play one.