After reading all of these replies, here's what I think about the singing issue. I don't think a singer post-surgery will ever lose the ability to sing. It's just that the range may be more limited after surgery. However, I think this might be a temporary thing. I would hazard a guess that after surgery, a singer is going to sound really hoarse for a while and after everything is healed, the vocal chords will have to be trained again to be able to sing in the new slightly more limited range. I would also hazard a guess (one too many hazards, I know) that over time a more acceptable range will just happen with training, perhaps not to extent of the original range, but something that, in itself, would be fine for the purposes of singing the way we wish to be heard. If I had the option to remove the lowest four notes of my singing range, why not? I wouldn't want to sound like a woman who sounds like a man. I wouldn't miss those four notes. I would just find a subset of the new range I am comfortable singing in and use that from that point on.
The more complicated question is not "can you sing?" but "when will you be able to sing?" since that depends on your healing time and motivation to train your new voice. In the end, our sound is basically air passing through a pipe. We are just working with a slightly smaller pipe post-surgery. (An overly simplistic explanation, I know, and it doesn't account for vibrations, resonance, and other factors that alter our sound.)