All we have are very general medical terms to describe his condition and we don't know the treatment he was receiving for anything.
Therefore we cannot know his prognosis and it was common for him to go years without touring or talking to media then do another round.
There are performers who tour unadvisedly and with chronic health conditions, who end up pushing themselves too hard. Michael Jackson's final tour was something that shouldn't even have been considered. People who were close to Elvis said they were very concerned about his health and that he needed a long break from performing to recover and get back in shape, but he needed the money from gigs so he kept going and delaying getting the treatment he needed.
In Edith Piaf's final performance, she had to be assisted up to the microphone to sing because she was physically handicapped but she could still sing.
Marlene Dietrich performed with Buerger's disease and wounds in her legs when she really should haven been in hospital. She just bandaged everything under her costume and kept taking antibiotics. Sarah Vaughan kept going nearly up to the end even with lung cancer. Audiences couldn't tell but backstage she was seen short of breath and wheezing terribly, relying on an oxygen tank.
Prince shouldn't have been on the road either and he didn't need the money but I guess that's all he had in his life.
GM too would keep performing in awful pain sometimes, which he suffered on and off. Once concerts are set up, you don't like to disappoint people.
People can die at relatively young age quite suddenly and unexpectedly, with few warning symptoms, and it is found that they actually had quite serious heart issues not detected previously. I know I'm at risk so I'm already taking precautions.
Some real know it alls here who know nothing of his real circumstances, were nowhere around him, but like to think they know everything. He was a complex person but the picture they want is a black and white one of somebody they say was totally fake and cared only about himself. That everything he did or said was only about himself and everything else dismissed out of hand. That's such an unfair insult and judgement to make about anyone and I don't understand that kind of blanket hate and negativity for someone you don't even know but apparently that's the only thought allowed here. I feel bad for anyone who feels like that in the end and wants to think the worst about everyone.
Some fans are in denial sure but not all. Many are aware of the flaws but if you defend him in any way here you get trounced on and called a delusional 'stan'. Extreme opposite end of places where they only want adoration and you can't have a real discussion about any other side of who he really was.
And been going on part 11 now of fairly pointless discussion going in circles by bunch of nobodies. I'm reminded why I usually avoid 'fan' discussions and rarely in it now. Moving on...