Elvis might have compromised his musical style a bit towards the end, but that doesn't mean that artists from the rock n' roll/folk-roots culture - of which he was not really a part - shouldn't get better as they get older, like the great jazz or blues artists.
Bonnie RaittHow I measure success is getting to make another record and being able to the come back to the same town and play again cause you sold out the last time.
Bonnie Raitt