Music is art - this isn't an athletic competition where he needs to be in tip top physical shape to write music people care about.

Joni Mitchell put out a record in 2007 called Shine - it was fantastic. Her age didn't keep her from recording a great record. In fact, she was singing about the world in a way most socially liberal adults could comprehend. That same year Prince was singing about working about a black sweat.

I don't think Prince's age has much to do with his inability to record an album's worth of music that people can get with. He appears to need someone to say, "Hey man, you're great and all that but Compassion and Beginning Endlessly kinda suck. Why don't you come back later and we'll try it all again?"