I guess it would be better to remove "timeless," as this is a term suggestive of infinity. Maybe we should think in terms of "multi-generational"--that the music survives/endures over 3 or 4 generations and many decades. Thus you have many fans, singers, musicians who continue to keep alive the likes of Miles, Trane, Sinatra, Hendrix, etc.
Certainly one has to feel that the works of Shakespeare and Mozart, having survived for centuries, will not be vanishing any time soon. Some 20th Century artists may have the same lasting power.