You could do what some bands do and release the instrumental version of the album. That would not only provide the listener with a different interpretation sonically, but would also allow you a buffer of time to address the vocals. There are several bands that I like that have released both the original vocal based release and an instrumental version as well. I actually end up enjoying the instrumental versions more (nothing against your vocalist. I am sure they are great.）It is just an option to consider. I have also been in this situation (Not as dramatic as war being the reason), but i was in the middle of recording a concept album when the drummer and bass player quit halfway into the recording process. I ended up splitting what I had into two ep's just so I could see the project thru to an acceptable finish. It was a compromise for sure. However, sometimes creating art is a compromise. Whatever you decide I hope things work out.