The best thing really is to speak with the doctors about it.
I know some folks think people should do everything possible even if it is just for a few more weeks of time. I'm not really one of those folks. My guess is that at 84, there are other health issues and going through a surgery like this would either be too risky or generally pointless.
If it is already spread locally, then chemo is already in order and getting an RC just makes life more complicated. If the doc thinks it isn't really going to extend his life anyway, then someone needs to discuss why he's even on chemo then. The doctor should be able to walk you (and him) through the pros and cons of doing the chemo and what the tradeoffs are.
Your dad may have to sign a release for the doctor to speak with you about it but you should get involved. Get the doctor's sense of the timing (general prognosis), how to know when he's moving from one phase to another and what to expect. At some point, palliative care is going to be the main thing. That is, pain management. Another thing to look into, depending on the prognosis, is hospice care. They are experts.
Sorry if my response seems clinical. I understand that this is a terrible time for him, you, and the rest of the family. It's terribly overwhelming and likely nobody who has spoken to the doctor heard more than a third of what was said. It's a scary time and emotions can really run wild.
Keep us in the loop. We don't know or understand everything but we've all thought about the potential of bladder cancer taking us out. We don't want to let that happen and we've each done all we can and we've also studied a lot because to know the enemy is important in defeating the enemy. However, sometimes in an ambush situation the only way to win is by having grace and poise under fire.
Mike