Daisy, sorry to be posting on this matter so late but I have been out of the country for 3 weeks and am just now catching up on the forum.
My Dad had RC at the age of 80 (he is now 83). He was in relatively good health except for the bladder (and, it turns out prostate) cancers. He wasn't big on exercising but he was in pretty good shape for his age. The day before his surgery he was up on the roof cleaning out the gutters!
He had complications with his surgery and had to go back into the hospital a second time the day after he was released and had to stay even longer the second time than for the original surgery. I think it was because we didn't know to seek out a highly experienced surgeon who did this operation on a regular basis although what happened could have happened with any doctor perhaps.
Dad has the ileal conduit and pouch. He also has stents in both ureters which are changed about every 3-4 months. He gets UTIs from time to time. It was really tough going for him at first especially with getting his bowels to work again (an ileus was one of the complications he had.) Also, the surgeon did not remove Dad's urethra and the cancer came back there so he had to have another surgery to remove that. He has been through a heck of a lot since being diagnosed. At one point, he questioned whether getting the surgery had been the right thing to do. I'm convinced it saved his life.
His surgery was in April of 2007 so we are approaching the 3-year mark soon. He has adjusted, I suppose, but he has never been the same, energy-wise, since the surgery. It seems as if he aged overnight. For the first time I can ever remember, he seems to act his age now.
We had to talk to a few doctors before we could find one who would operate on a man Dad's age, but they are out there. Maybe you should get a second opinion.
Best of luck to you and your father-in-law.